Expression of iron binding proteins and hemin binding activity in the dental pathogen Actinobacillus actinomycetemcomitans

• Published in: FEMS microbiology letters 1998-06, Vol.163 (2), p.135-142
• Main Authors: Graber, Katherine R., Smoot, Laura M., Actis, Luis A.
• Format: Article
• Language: English
• Subjects: A. actinomycetemcomitans; Actinobacillus actinomycetemcomitans; Aggregatibacter actinomycetemcomitans - genetics; Aggregatibacter actinomycetemcomitans - metabolism; Amino acid sequence; Amino acids; Bacterial Outer Membrane Proteins - biosynthesis; Bacterial Outer Membrane Proteins - genetics; Bacterial Proteins - biosynthesis; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Biological and medical sciences; Blotting, Northern; Blotting, Western; Carrier Proteins - biosynthesis; Carrier Proteins - genetics; Cloning; Congo Red - metabolism; Cultivation; E coli; Electrophoresis, Polyacrylamide Gel; Escherichia coli - genetics; Escherichia coli - metabolism; FbpA; FimA; Fimbriae Proteins; Fundamental and applied biological sciences. Psychology; Fur; Gene expression; Gene Expression Regulation, Bacterial; Genes, Bacterial; Genetics; Haemophilus influenzae - genetics; Haemophilus influenzae - metabolism; Hemeproteins - biosynthesis; Hemeproteins - genetics; Hemin; Hemin - metabolism; hitABC gene; Homology; Humans; Iron; Iron - metabolism; Iron binding protein; Iron-Binding Proteins; Microbiology; Pathogens; Periodontitis - microbiology; Periplasmic Binding Proteins; Periplasmic space; Polypeptides; Proteins; Repressor Proteins - genetics; Repressor Proteins - metabolism
• ISSN: 0378-1097; 1574-6968
• DOI: 10.1111/j.1574-6968.1998.tb13037.x

Abstract Actinobacillus actinomycetemcomitans was found to express a polypeptide immunologically related to the Neisseria gonorrhoeae FbpA iron binding protein. In addition, the expression of hitB and hitC homologs was detected by Northern blot analysis. This periodontal pathogen also expresses a polypeptide homologous to the 31-kDa Haemophilus influenzae protein, which shows amino acid sequence homology with the FimA and YfeA proteins from Streptococcus parasanguis and Yersinia pestis, respectively. Both A. actinomycetemcomitans protein homologs were located within the periplasmic space, and their synthesis was regulated by the iron and hemin concentration of the culture medium. Southern and Western blot analysis together with molecular cloning revealed the presence of a Fur-like repressor, which may control the iron regulation of gene expression in this bacterium. Cultivation in the presence of hemin or Congo red revealed the ability of this organism to bind hemin. This binding activity was further confirmed by isolating Escherichia coli DH5α clones that produced red and brown colonies on agar plates containing Congo red and hemin, respectively, after transformation with an A. actinomycetemcomitans gene library.