Haemophilus influenzae polypeptides involved in deoxyribonucleic acid uptake detected by cellular surface protein iodination

Polypeptides that appear to be involved in competence development and deoxyribonucleic acid (DNA) uptake by Haemophilus influenzae were detected with a surface-specific iodinating reagent 1,3,4,6,-tetrachloro-3 alpha, 6 alpha-diphenylglycoluril. As shown on electrophoretograms, a number of polypeptides became sensitive to 125I protein labeling with the ability of these cells to bind DNA. Of these polypeptides, nine were reduced in their ability to be labeled (ral polypeptides) extensively after the incubation of competent cells with homologous, but not with heterologous, DNA. Iodination of many of these ral polypeptides was reduced in competence-deficient mutants compared with wild-type competent cells. One 125I-labeled polypeptide corresponding to a molecular weight of 29,000 was present at reduced levels in mutants reduced in the ability to bind DNA. Our results suggest that the 29,000-molecular-weight polypeptide corresponds with the ability of H. influenzae to take up DNA and that a complex of proteins is involved in DNA uptake and transformation.