4OKO

Crystal structure of Francisella tularensis REP34 (Rapid Encystment Phenotype Protein 34 KDa)

Summary for 4OKO

• Entry DOI: 10.2210/pdb4oko/pdb
• Descriptor: Rapid Encystment Phenotype Protein 34 KDa, ZINC ION, ACETATE ION, ... (4 entities in total)
• Functional Keywords: carboxypeptidase, secreted, hydrolase
• Biological source: Francisella tularensis subsp. novicida
• Total number of polymer chains: 4
• Total formula weight: 142024.38

Authors

Feld, G.K.,Segelke, B.W.,Corzett, M.H.,Hunter, M.S.,Frank, M.,Rasley, A. (deposition date: 2014-01-22, release date: 2014-09-24, Last modification date: 2024-04-03)

Primary citation

Feld, G.K.,El-Etr, S.,Corzett, M.H.,Hunter, M.S.,Belhocine, K.,Monack, D.M.,Frank, M.,Segelke, B.W.,Rasley, A.
Structure and Function of REP34 Implicates Carboxypeptidase Activity in Francisella tularensis Host Cell Invasion.
J.Biol.Chem., 289:30668-30679, 2014

PubMed Abstract: Francisella tularensis is the etiological agent of tularemia, or rabbit fever. Although F. tularensis is a recognized biothreat agent with broad and expanding geographical range, its mechanism of infection and environmental persistence remain poorly understood. Previously, we identified seven F. tularensis proteins that induce a rapid encystment phenotype (REP) in the free-living amoeba, Acanthamoeba castellanii. Encystment is essential to the pathogen's long term intracellular survival in the amoeba. Here, we characterize the cellular and molecular function of REP34, a REP protein with a mass of 34 kDa. A REP34 knock-out strain of F. tularensis has a reduced ability to both induce encystment in A. castellanii and invade human macrophages. We determined the crystal structure of REP34 to 2.05-Å resolution and demonstrate robust carboxypeptidase B-like activity for the enzyme. REP34 is a zinc-containing monomeric protein with close structural homology to the metallocarboxypeptidase family of peptidases. REP34 possesses a novel topology and substrate binding pocket that deviates from the canonical funnelin structure of carboxypeptidases, putatively resulting in a catalytic role for a conserved tyrosine and distinct S1' recognition site. Taken together, these results identify REP34 as an active carboxypeptidase, implicate the enzyme as a potential key F. tularensis effector protein, and may help elucidate a mechanistic understanding of F. tularensis infection of phagocytic cells.

PubMed: 25231992
DOI: 10.1074/jbc.M114.599381

Experimental method

X-RAY DIFFRACTION (2.053 Å)