Picture of S. Peter Howard

S. Peter Howard Emeritus Professor Biochemistry, Microbiology & Immunology

Health Science Bldg., 107 Wiggins Rd, Saskatoon SK S7N 5E5

Research Area(s)

  • Molecular biology of toxin secretion by Gram-negative bacteria
  • Structure, function and biogenesis of the outer membrane


Areas of Expertise

Molecular Genetics, Microbial Physiology

Recent Publications

Vanderlinde EM, Zhong S, Li G, Martynowski D, Grochulski P, Howard SP.  Assembly of the type two secretion system in Aeromonas hydrophila involves direct interaction between the periplasmic domains of the assembly factor ExeB and the secretin ExeD.  PLoS One. 2014 Jul 15;9(7):e102038.

Strozen TG, Li G, Howard SP.  YghG (GspSβ) is a novel pilot protein required for localization of the GspSβ type II secretion system secretin of enterotoxigenic Escherichia coli.  Infect Immun. 2012 Aug;80(8):2608-22.

Strozen, T.G., H. Stanley, Y. Gu, J. Boyd, M. Bagdasarian, M. Sandkvist, and S. P. Howard. 2011. Involvement of the GspAB complex in assembly of the type II secretion system secretin of Aeromonas and Vibrio species. Journal of Bacteriology. 193:2322-2331.

Li, G., A. Miller, H. Bull, and S. P. Howard. 2011. Assembly of the type II secretion system: Identification of ExeA residues critical for peptidoglycan binding and secretin multimerization. Journal of Bacteriology. 193:197-204.

Li, G. and S. P. Howard. 2010. ExeA binds to peptidoglycan and forms a multimer for assembly of the type II secretion apparatus in Aeromonas hydrophila. Molecular Microbiology. 76:772-781.

Kohler, S.D., A. Weber, S.P. Howard, W. Welte and M. Drescher. 2010. The proline-rich domain of TonB possesses an extended polyproline II-like conformation of sufficient length to span the periplasm of Gram-negative bacteria. Protein Science 19:625-630.

Stefureac, R., L. Waldner , S.P. Howard and J.S. Lee. 2008. Nanopore analysis of a small 86-residue protein. SMALL 4:59-63.

Garcia-Herrero, A., R.S. Peacock, S.P. Howard and H. Vogel. 2007. The solution structure of the periplasmic domain of the TonB system ExbD protein reveals an unexpected structural homology with siderophore-binding proteins. Molecular Microbiology 66:872-889.

Howard, S.P., C. Geall, G.R. Langen and G. Li. 2006. Interactions between the ExeAB complex and peptidoglycan during assembly of the type II secretin of Aeromonas hydrophila. Molecular Microbiology 59:1062-1072.

Stefureac, R., Y-T. Long, H-B. Kraatz, S. P. Howard, and J. S. Lee. 2006. Transport of a-helical peptides through a-hemolysin and aerolysin pores. Biochemistry 45: 91272-9179.

Schoenhofen, I.C., G. Li, T.G. Strozen, and S.P. Howard. 2005. Purification and characterization of the N-terminal domain of ExeA: A novel ATPase involved in the type II secretion pathway of Aeromonas hydrophila Journal of Bacteriology. 187:6370-6378.

Strozen, T.G., G.M. Langen and S.P. Howard. 2005. Adenylate cyclase mutations rescue the degPtemperature sensitive phenotype and induce the Sigma E and Cpx extracytoplasmic stress regulons in Escherichia coli Journal of Bacteriology. 187:6309-6316.

Yu, H.B., Y.L. Zhang, F. Yao, S. Vilches, S. Merino, J.M. Tomas, S.P. Howard, and K.Y. Leung. 2005. Identification and characterization of putative virulence genes and gene clusters in Aeromonas hydrophila PPD134/91. Applied and Environmental Microbiology. 71:4469-4477.

Peacock, S.R; Weljie, A.M; Howard, SP; Price, F; and Vogel, H.J. 2005. Solution Structure of the C-Terminal Domain of TonB and its Interaction with the TonB Box. J. Mol. Biol. 345:1185-1197.

Koedding, J; Killig, F; Polzer, P; Howard, S.P; Diederichs, K; and Welte, W. 2005. Crystal structure of a 92-residue C-terminal fragment of TonB from Escherichia coli reveals significant conformational changes compared to structures of smaller TonB fragments J. Biol. Chem. 280:3022-3028.

Koedding, J; Howard, SP; Kaufmann, L; Polzer, P; Lustig, A; Welte, W. 2004. Dimerization of TonB is not essential for its binding to the outer membrane siderophore receptor FhuA of Escherichia coli. J. Biol. Chem. 279:9978-9986.

Koedding, J; Polzer, P; Killig, F; Howard, SP; Gerber, K; Seige, P; Diederichs, K; and Welte, W. 2004. Crystallization and preliminary X-ray analysis of a C-terminal TonB fragment from Escherichia coli. Biol. Crystallography. 60:1281-1283.

Sauter, A; Howard, SP; Braun, V. 2003. In vivo evidence for TonB dimerization. J. Bacteriology. 185: 5747-5754.

Ast, V. A., I. C. Schoenhofen, G. R. Langen, C. W. Stratilo, M. D. Chamberlain, and S. P. Howard (2002). Expression of the ExeAB complex of Aeromonas hydrophila is required for the localization and assembly of the ExeD secretion port multimer. Mol. Microbiol. 44: 217-31.

Langen G. R., J. R. Harper, T. J. Silhavy, and S. P. Howard (2001). The absence of the outer membrane phospholipase A suppresses the temperature sensitive phenotype of Escherichia coli degp mutants and induces the cpx and ?e extracytoplasmic stress responses. J. Bacteriol. 183: 5230 – 38.

Howard,S. P., C. Herrmann, C. W. Stratilo, and V. Braun (2001). In Vivo Synthesis of the Periplasmic Domain of TonB Inhibits Transport through the FecA and FhuA Iron Siderophore Transporters of Escherichia coli. J. Bacteriol. 183: 5885 - 95.

Member of the molecular design research group