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Structural determinants of autoproteolysis of the Haemophilus influenzae Hap autotransporter

Kenjale, R. and Fink, D.L. and Juehne, T. and Ohashi, T. and Erickson, H.P. and Meng, G.Y. and Waksman, Gabriel and St. Geme, J.W. (2009) Structural determinants of autoproteolysis of the Haemophilus influenzae Hap autotransporter. Infection and Immunity 77 (11), pp. 4704-4713. ISSN 0019-9567.

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Official URL: http://dx.doi.org/10.1128/IAI.00598-09

Abstract

Haemophilus influenzae is a gram-negative bacterium that initiates infection by colonizing the upper respiratory tract. The H. influenzae Hap autotransporter protein mediates adherence, invasion, and microcolony formation in assays with respiratory epithelial cells and presumably facilitates colonization. The serine protease activity of Hap is associated with autoproteolytic cleavage and extracellular release of the HapS passenger domain, leaving the Hapβ C-terminal domain embedded in the outer membrane. Cleavage occurs most efficiently at the LN1036-37 peptide bond and to a lesser extent at three other sites. In this study, we utilized site-directed mutagenesis, homology modeling, and assays with a peptide library to characterize the structural determinants of Hap proteolytic activity and cleavage specificity. In addition, we used homology modeling to predict the S1, S2, and S4 subsite residues of the Hap substrate groove. Our results indicate that the P1 and P2 positions at the Hap cleavage sites are critical for cleavage, with leucine preferred over larger hydrophobic residues or other amino acids in these positions. The substrate groove is formed by L263 and N274 at the S1 subsite, R264 at the S2 subsite, and E265 at the S4 subsite. This information may facilitate design of approaches to block Hap activity and interfere with H. influenzae colonization.

Item Type: Article
School or Research Centre: Birkbeck Schools and Research Centres > School of Science > Biological Sciences
Depositing User: Administrator
Date Deposited: 04 Aug 2010 14:09
Last Modified: 17 Apr 2013 12:17
URI: http://eprints.bbk.ac.uk/id/eprint/1173

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