The Aldehyde Oxidase Gene Cluster in Mice and Rats

Mammalian molybdo-flavoenzymes are oxidases requiring FAD and molybdopterin (molybdenum cofactor) for their catalytic activity. This family of proteins was thought to consist of four members, xanthine oxidoreductase, aldehyde oxidase 1 (AOX1), and the aldehyde oxidase homologues 1 and 2 (AOH1 and AOH2, respectively). Whereas the first two enzymes are present in humans and various other mammalian species, the last two proteins have been described only in mice. Here, we report on the identification, in both mice and rats, of a novel molybdo-flavoenzyme, AOH3. In addition, we have cloned the cDNAs coding for rat AOH1 and AOH2, demonstrating that this animal species has the same complement of molybdo-flavoproteins as the mouse. The AOH3 cDNA is characterized by remarkable similarity to AOX1, AOH1, AOH2, and xanthine oxidoreductase cDNAs. Mouse AOH3 is selectively expressed in Bowman's glands of the olfactory mucosa, although small amounts of the corresponding mRNA are present also in the skin. In the former location, two alternatively spliced forms of the AOH3 transcript with different 3′-untranslated regions were identified. The general properties of AOH3 were determined by purification of mouse AOH3 from the olfactory mucosa. The enzyme possesses aldehyde oxidase activity and oxidizes, albeit with low efficiency, exogenous substrates that are recognized by AOH1 and AOX1. The to mouse 1 and rat in to the and and has to that of the other in the two Mammalian molybdo-flavoenzymes are oxidases requiring FAD and molybdopterin (molybdenum cofactor) for their catalytic activity. This family of proteins was thought to consist of four members, xanthine oxidoreductase, aldehyde oxidase 1 (AOX1), and the aldehyde oxidase homologues 1 and 2 (AOH1 and AOH2, respectively). Whereas the first two enzymes are present in humans and various other mammalian species, the last two proteins have been described only in mice. Here, we report on the identification, in both mice and rats, of a novel molybdo-flavoenzyme, AOH3. In addition, we have cloned the cDNAs coding for rat AOH1 and AOH2, demonstrating that this animal species has the same complement of molybdo-flavoproteins as the mouse. The AOH3 cDNA is characterized by remarkable similarity to AOX1, AOH1, AOH2, and xanthine oxidoreductase cDNAs. Mouse AOH3 is selectively expressed in Bowman's glands of the olfactory mucosa, although small amounts of the corresponding mRNA are present also in the skin. In the former location, two alternatively spliced forms of the AOH3 transcript with different 3′-untranslated regions were identified. The general properties of AOH3 were determined by purification of mouse AOH3 from the olfactory mucosa. The enzyme possesses aldehyde oxidase activity and oxidizes, albeit with low efficiency, exogenous substrates that are recognized by AOH1 and AOX1. The to mouse 1 and rat in to the and and has to that of the other in the two are a of requiring molybdopterin (molybdenum cofactor) and a for their catalytic activity proteins are present from to In four molybdo-flavoenzymes have been xanthine oxidoreductase xanthine AOX1, aldehyde oxidase AOH1, AOH2, and aldehyde oxidase homologues of cDNA expressed 3′-untranslated aldehyde oxidase 1 and aldehyde oxidase homologues 1 and 2 (AOH1 and AOH2, Whereas and have been and characterized in humans and AOH1 and have been only in mice Mammalian molybdo-flavoenzymes are proteins of of two The of the of of the family is a from a AOX1, AOH1, and are the of that This that the of the mammalian family from In to and aldehyde oxidase on 1 is a present in and although is in amounts in the and the of to xanthine and xanthine to a enzyme in the of the have other as by the in the mouse is the and substrates of the other of the and AOH1 are expressed in the and and is the of a and a of and in the and AOH1 of to the of and the of of in is the of In the enzyme is to as is present in low only in is enzyme of and In this aldehyde oxidase as and and as The enzyme has also been in the of in humans and other as the that AOH1 a in the on mouse and AOH1 that is a for the two enzymes In addition, in mouse characterized by the of different of both AOH1 and the same of in In this we that the family of mammalian molybdo-flavoenzymes is In we have and mouse a novel characterized by similarity to AOX1, AOH1, AOH2, to a The is with aldehyde oxidase activity and is selectively expressed in the the of Bowman's The corresponding cDNAs have been cloned and in both the mouse and of the mouse and rat AOH3 cDNAs in the of the of the corresponding are on 1 and we have also cloned and the cDNAs of the mouse AOH1 and proteins in rats, demonstrating that the two are for by that with and on last that the of forms of aldehyde oxidases in is a of the mouse. and of cDNAs for Mouse AOH3 and AOH1, AOH2, and was from mouse olfactory mucosa, and the of the was to The mouse AOH3 cDNA expressed in olfactory was as two and by by The for were as and to and to and to The and were with the and The mouse AOH3 cDNA was also from in a and was AOH1, AOH2, and AOH3 cDNAs were from and olfactory by coding for the first and corresponding to the and the The cDNA the coding regions of were in and of the and of the Mouse AOH3 and of cDNA for the mouse AOH3 cDNAs were with the cDNA to the and the to of the mouse AOH3 and to of the mouse AOH3 of the mouse AOH3 cDNAs was as described with the and The were in and were to the and of the mouse AOH3 In was with and as for the of in the of as described Mouse were in in to and on The for the of and by the were as described in a report the of the in were with and a of Mouse AOH3 and purification were mouse olfactory was and in of with were for to were for and to of was to the and the was by and in The was a to the The was to a in The AOH3 was with a of in The purification of AOH3 was by a of the was for was a as described This is and with mouse and AOH1 and mouse AOX1, AOH1, and expressed in of purification was on the same and for corresponding to AOH3 were with a The of AOH3 in the various is expressed in and was on the of the of the in by the of purification of to of the AOH3 in of activity was on were with and the enzyme was to were to the with a of the AOH3 by and of AOH3 were to the corresponding to AOH3 was with in for to were with in in the for was in and were in and The were in and were in and The was with a of in and of was with a The were with the a of was on The were by of the and of the from the AOH3 from the corresponding and of the of the Mouse and and were the and to the as and were by of the was the of the and of the cDNAs corresponding to mouse AOH3 and rat AOH1, AOH2, and AOH3 with the mouse and rat present in the in the of the of the corresponding and of the Mouse cDNA for the of the for of the mouse similarity to the AOX1, AOH1, and cDNAs in the of coding for a and novel we AOH3. The were for the of that the of cDNA of mouse AOH3 by from olfactory from The first of AOH3 was on the of a in the mouse expressed 1 the of the AOH3 cDNA from mouse olfactory mucosa. The is and a of the first that is to the The 3′-untranslated is and is characterized by the of a this of the cDNA was by the of a is to the of the of In a is present in the mouse of the corresponding to the last of AOH3 two present in the and corresponding to the 3′-untranslated of the AOH3 transcript and to the The of the olfactory AOH3 cDNA is different from that of the corresponding mouse cDNA and is the of a of the mouse are in and are in The of to the and of the are the is the same as that of the AOH3 cDNA the are the The in that as is as a in in a The for a of and is that of AOX1, AOH1, and This is to the of in the the FAD and of the and from a in the of the of the of and The AOH3 is with the of the mouse as in other of the family the of AOH3 the corresponding to the two In AOH3 the for the of the are by a that to the the The of AOH3 is characterized by a of to the corresponding of AOX1, AOH1, and AOH2, This is with the only also to is in the of AOX1, AOH1, and AOH2, the that is by in and that is in is present in AOH3. the and of AOH3. In the last of the of is of mouse AOH2, AOH1, AOX1, and The of mouse AOH3 is with of AOH2, AOH1, and the are from the to the from the first of The in to the AOH3 present in other AOH3 are in to the The corresponding to the two are In the the the of the to in the of the The of mouse to the determined for The of the different of the and The the for the of the The two the of the of the corresponding are by the and the of in of the of has to the of and in to the as in and enzyme The in mouse are and is in AOH3 and the other mouse aldehyde that the is for the of The two and are in AOH3 with the two and This is to is in mouse AOX1, AOH1, and with the that is for the of the and xanthine in the AOX1, AOH1, and AOH2, the two substrates of the of mouse AOH3 from that the enzyme is a of the In addition, are with the that AOH3 is to AOX1, AOH1, and to with the and the that the to the of aldehyde oxidases and the and the of the cDNAs for the AOH2, and AOH1 of the and proteins have been in various species AOH1 and have been described only in the mouse The of the cDNA coding for AOH3 and the of the first of the rat to the of to the various mouse aldehyde oxidase homologues in this animal of the rat for four aldehyde oxidase as in the mouse cloned cDNAs the coding regions of rat AOH1, AOH2, and AOH3. the of the from the rat AOH1, AOH2, and AOH3 cDNAs with the corresponding mouse and mouse AOH3 are the two molybdo-flavoproteins that the of similarity by the AOH1 and with the of similarity in the of rat and mouse as as rat and mouse on the of is the molybdo-flavoenzymes rat AOH1, AOH2, and AOH3 are characterized by a of in the corresponding to the This of the for the of the are the present in the regions of the of mouse and rat AOH3 are characterized by the of This for a present in and proteins of different and a in mouse rat AOH1 and AOH1, AOH2, and AOH3 to the with to the of in mouse and other proteins to is in the of the mouse this is to in rat AOH1, AOH2, and AOH3. that and mice and the same complement of aldehyde oxidase AOH3 in the and for AOH3 in the of the in that the only demonstrating of the AOH3 transcript of is the olfactory mucosa. The transcript was from other the and two of the that are in and amounts of AOH3 mRNA were present also in the and were only of the in the The of AOH3 is different from that of the other mouse AOX1, AOH1, and In and AOH1 are in the of the and in the of the the of is The of the AOH3 transcript with that of AOH2, is expressed in the of as as in the of the and the first of the of various AOH3 cDNA from the olfactory and the of different 3′-untranslated regions in the two In we that the of the last of the of AOH3 expressed in the olfactory is in of the the last of the olfactory AOH3 transcript to of on mouse 1 and the and the has been we determined the of this of by a of corresponding to the two is of of the of the of a to the the the of the AOH3 present in the and olfactory The is of the of the AOH3 of the of the of a to and of the the of the olfactory this that a is the of the the of the AOH3 expressed in the olfactory and skin. this we corresponding to and corresponding to the of as as to the of and the of The were in the in a was by 1 and 2 in both the and olfactory mucosa. the of 1 and the of a cDNA in the two In the of the last and a was only with from the This that the olfactory a of AOH3 with different and of the for the of the two AOH3 The and of this are The olfactory of the olfactory the olfactory and the olfactory The olfactory is of the olfactory mucosa, is in the and of that their to the of the olfactory of the to the are The last of the to a and the olfactory the are to other regions of the the of AOH3 and other of the family in the various of the olfactory with were in a of corresponding to the of AOH3 was in the from the olfactory was in the of the olfactory and The is to that of was also expressed in the olfactory in the In AOX1, AOH1, and were expressed in of the olfactory the proteins were in the corresponding that AOH3 is present only in the of the olfactory and that the only other present in this is The of mouse and AOH1 is as the two enzymes are expressed in amounts in the and of the of AOX1, AOH1, and is on the mouse mouse as amounts of AOH1 and amounts of in the In mice as and are selectively and in the of AOH1 and amounts of in the by the in the of AOH1 and is in the of and and mice. the of AOH3 in the olfactory was by the by the of the as of the were present in both and and mice. that only the coding for and AOH1, coding for AOH3 as and to and that as the of in the of the in mice a in the of aldehyde oxidase is for of the mammalian aldehyde oxidases and is by AOH3 as The in that the of from the olfactory of activity. on this activity was two the corresponding to AOH3 a to that of mouse AOH1 also and was from the corresponding to on that the AOH3 in the olfactory is as with the of AOH3 in the The olfactory of the olfactory the and a the glands for the of the the are the of AOH3 in the olfactory mucosa, we a of in a the transcript coding for this aldehyde oxidase The in a of the of a mouse. This is characterized by the of the olfactory the of Bowman's glands are the of of the In this is that the AOH3 mRNA is the of the of Bowman's The determined with the AOH3 is as the corresponding as a in the of a of on that the of the corresponding to the AOH3 mRNA is the of the of the a of the mouse olfactory of the olfactory the and the is characterized by the of Bowman's glands and the corresponding The olfactory two the are for the and of the and the a The are to have the same as the the and of Bowman's glands The in of AOH3 mRNA in the of the olfactory mucosa. In this the is with the of the AOH3 transcript in the and of Bowman's as in AOH3 mRNA is also in the of the olfactory the of is The of the olfactory is for the of AOH3. and of Mouse the of AOH3 and to and AOH3 was from the olfactory mucosa. AOH3 was to by and of for AOH3 from a and to the purification of the that AOH3 is a in the olfactory mucosa. In purification to in of to the The of the was and was that in the of mouse and AOH1 This is the of the that AOH3 purification the on that is for the of both and AOH1 the amounts of AOH3 were on the of from of to from the last purification on AOH3 a that the was that the AOH3 from the only other in the olfactory In with and and the AOH3 was recognized by the by the that the AOH3 was as of a of and and to the was and and the was to in the was different from that of the other mouse AOH1, we from and mouse of mouse AOH3 AOH3 was to from the of mice. The purification of AOH3 was by The amounts of AOH3 determined purification were by and are expressed in The activity of the AOH3 purification was by the in the by the corresponding in the The are of purification in a that from the AOH3 on the of the of the from the of the cloned AOH3 are to of two with the the and determined is the of the of mouse AOH3 in the the determined for the in This that the from the olfactory to mouse AOH3. The of of were determined by with the by of from AOH3 and of AOH3 from mouse olfactory was and to the was to with a to the in the first are the The in the are from the in of the The the of the AOH3 The the corresponding The and the the in the first are the The the of The the with the in a by the in AOH3 is a enzyme and and substrates of and AOH1 AOH3 the with a to that of mouse AOH1, was as a in AOH3 has the to the In amounts of AOH1 were in the substrates to the that the of AOH3 and AOH1 is that the catalytic is In addition, that is the for AOH3 the of of is that and AOH1, substrates and and the corresponding to AOH3 was of activity This that the novel has low for this and that AOH3 is to AOX1, AOH1, and to only in of also in of in Mouse and of the mouse AOH3 cDNA as as the rat AOH1, AOH2, and AOH3 cDNAs to the of the corresponding in mouse is from of the novel on 1 the of the aldehyde oxidase the mouse of the four and are a from and are from the same and in the same of the and is on of the rat The the rat and are of to of the corresponding mouse The of the mouse and rat aldehyde oxidase are and from in the of to in the of The of the mouse is in The is of coding and has the to the last of the 3′-untranslated of the transcript expressed in the olfactory to this last to a also to the rat for with of the of the mouse to the in other the of similarity the cDNA and is that this is also in the of the rat and the of the and the and of of the coding of the mouse are in mouse and as in of are in mouse and of the is in the mouse and rat and and The of is different in mouse to other of the This is the of the that is the corresponding in and and for the the the FAD with the have for the of the AOH3 In the of mouse is in the rat in the of a with a for mouse and in the of mouse as as rat and the of are The of the that AOH3 has the same as other of the family and from the same is that coding of the two species are of the coding of the and in mouse and rat a to the of the regions by in this in we first the of similarity of the coding of in this is in the of by and we determined the of a of similarity the of the and the of the the corresponding that the first of we are are of for the In the of we are to for of that are for the of the in the of the only are of the and are in that for and general of the corresponding of for in the and regions of the the other is to the aldehyde oxidase and the of a and other of the mammalian The and and are only in and are only in coding for for 1 and are only in and the of are in the of the the present in to the and and are in of the various is that is in and as for of the the and the similarity of the rat and mouse and The of similarity corresponding of the mouse and rat and was The of the for was determined and is the a of similarity the of the of are with the similarity in a of similarity the are with the similarity in The was to the the that of is by is present in and of to of and that of is by is present in and of to of and that of is by is present in and of to of and that of is by is present in and of to of and that of is by is present in and of to of and that of is by is present in and of to of and that of is by is present in and of to of and that of is by is present in and of to of and in a The of this are the and of a novel of the family with aldehyde oxidase as as the of the of the aldehyde oxidase in mouse and The of AOH3 the of mammalian molybdo-flavoenzymes to of a in the of the mouse and of the first of the rat the of novel coding for In of the two to coding for a novel of the The two are expressed in the of a mRNA in mouse and as by of the corresponding cDNAs. In addition, the mouse AOH3 transcript is a enzyme that to from the olfactory mucosa. of the mouse and rat cDNAs that the proteins have the of the of mammalian the of two a FAD and a is that other of the is a of the is that this is the In in the of are in mouse and rat AOH3. of the of AOH3 that the is to mouse and rat AOX1, AOH1, and to the other molybdo-flavoenzyme, This that the novel as a aldehyde This is by the mouse and rat AOX1, AOH1, and as as aldehyde oxidases of and the present in the of and in other This is of for the of as the xanthine and the of the on the of this last mouse AOX1, AOH1, and AOH2, and xanthine to a purification of AOH3 from the mouse that the enzyme possesses aldehyde oxidase as various and as as are recognized substrates of both and AOH1 AOH3 to substrates AOH1 and is to the this is that the enzyme has a for substrates the other of the mammalian aldehyde oxidase is that AOH3 is only a of the enzyme is in as in the of the amounts of AOH3 that from the olfactory a of the and of the AOH3 is with a of and in the mouse. In although small amounts of the AOH3 transcript and of the corresponding as are in the the and only other of the enzyme is the olfactory mucosa. The amounts of AOH3 mRNA expressed in the to the for the of the transcript in In this is that AOH3 with the other aldehyde AOH2, is in the of the of mouse AOH3 in the olfactory is of remarkable as are This the that AOH3 is in the of of in the mammalian this is the the enzyme have as AOH3 is present in the of the olfactory the olfactory are and is in of the other for the of the In in are with a of AOH3 in the and of Bowman's glands that are in the of the olfactory mucosa. a of AOH3 mRNA is also in olfactory are thought to have the same as the of Bowman's glands The of AOH3 in the is with a of the enzyme in the of of the is also that AOH3 is in the and of and in the of the olfactory that the olfactory is that the of the AOH3 transcript in the olfactory is of that of a of the family of is in the of the and in the of the olfactory The family of proteins is in the of of and and the various are to the of the and that This of is in the of various and of and AOH3 in the same the olfactory that the two enzymes have in the same a of the of the of the cDNAs coding for mouse AOH3 and the rat of AOH2, and AOH1 the of the and of the corresponding The mouse remarkable of the to and of the aldehyde oxidase the of rat and is on that of the that from This last that the of coding for mammalian molybdo-flavoenzymes with aldehyde oxidase activity is a of the mouse. The mouse to the same 1 and are in the same as and a of rat the rat In both animal species, the on a different in mouse and in This is with a of this last molybdo-flavoenzyme, aldehyde to The complement of molybdo-flavoenzymes is to that of of and In and four forms of molybdo-flavoenzymes to AOX1, AOH1, AOH2, and AOH3. proteins as aldehyde oxidases on the of various in mice and rats, are for by with the corresponding a of the to the of and are and have In the of and aldehyde oxidase is and different from that of mammalian aldehyde oxidase This with the of the mammalian molybdo-flavoproteins and the of the of the corresponding that mouse and rat AOX1, AOH1, AOH2, and AOH3 The of the first of the and to a the of the in two other The of coding for of are characterized by remarkable similarity to and The first to and is characterized by that are with the that the for the The other four are to on and present with the of the rat aldehyde oxidase and the of the on the of the of the mouse and rat This that the to the complement of mammalian the of from The of the is In this animal species, is for the and two coding for proteins characterized by similarity to AOX1, AOH1, AOH2, AOH3. to the other two to a from other and This that are with aldehyde oxidase and that to as in the of rats, and of the and two aldehyde oxidase homologues and to of the The molybdo-flavoenzymes are as corresponding to the of are present in the this that are with a complement of that is that of and This that the of the of the mammalian family was and that a first of The of is by the of In the complement of and proteins the is on the of present in and aldehyde oxidase and the corresponding the have been to other although a of of the to for proteins and are to albeit to although in this animal species, a of the complement only on the of the for to AOX1, AOH1, AOH2, AOH3 in the of only two of cDNAs. The two to coding for and a aldehyde oxidase and this is to is in In that the aldehyde oxidase present in and for proteins that that are that have in of In of aldehyde oxidases for that are that have been in humans and with this the last to the is expressed in the olfactory is and in and in the same is present in amounts in the of the a in the of the of is a that is different in humans to other the of molybdo-flavoenzymes as as the for other animal species of the for aldehyde oxidase that we have that we are in the of and for for and for are also to for of the are to of for the on the of AOH3 the olfactory mucosa.