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Type II secretion-dependent aminopeptidase LapA and acyltransferase PlaC are redundant for nutrient acquisition during Legionella pneumophila intracellular infection of amoebas

DOI: 10.1128/mBio.00528-18 DOI Help

Authors: Richard C. White (Northwestern University) , Felizza F. Gunderson (Northwestern University) , Jessica Y. Tyson (Northwestern University) , Katherine H. Richardson (Queen Mary University of London) , Theo J. Portlock (Queen Mary University of London) , James A. Garnett (Queen Mary University of London) , Nicholas P. Cianciotto (Northwestern University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Mbio , VOL 9

State: Published (Approved)
Published: May 2018
Diamond Proposal Number(s): 12579

Open Access Open Access

Abstract: Legionella pneumophila genes encoding LapA, LapB, and PlaC were identified as the most highly upregulated type II secretion (T2S) genes during infection of Acanthamoeba castellanii, although these genes had been considered dispensable on the basis of the behavior of mutants lacking either lapA and lapB or plaC. A plaC mutant showed even higher levels of lapA and lapB transcripts, and a lapA lapB mutant showed heightening of plaC mRNA levels, suggesting that the role of the LapA/B aminopeptidase is compensatory with respect to that of the PlaC acyltransferase. Hence, we made double mutants and found that lapA plaC mutants have an ~50-fold defect during infection of A. castellanii. These data revealed, for the first time, the importance of LapA in any sort of infection; thus, we purified LapA and defined its crystal structure, activation by another T2S-dependent protease (ProA), and broad substrate specificity. When the amoebal infection medium was supplemented with amino acids, the defect of the lapA plaC mutant was reversed, implying that LapA generates amino acids for nutrition. Since the LapA and PlaC data did not fully explain the role of T2S in infection, we identified, via proteomic analysis, a novel secreted protein (NttD) that promotes infection of A. castellanii. A lapA plaC nttD mutant displayed an even greater (100-fold) defect, demonstrating that the LapA, PlaC, and NttD data explain, to a significant degree, the importance of T2S. LapA-, PlaC-, and NttD-like proteins had distinct distribution patterns within and outside the Legionella genus. LapA was notable for having as its closest homologue an A. castellanii protein.

Journal Keywords: Acanthamoeba; acyltransferase; aminopeptidase; Legionella pneumophila; Legionnaires' disease; protease; type II secretion; intracellular infection

Diamond Keywords: Legionnaires' Disease; Bacteria; Enzymes

Subject Areas: Biology and Bio-materials

Instruments: I03-Macromolecular Crystallography

Added On: 25/04/2018 11:56


Discipline Tags:

Pathogens Infectious Diseases Health & Wellbeing Structural biology Life Sciences & Biotech

Technical Tags:

Diffraction Macromolecular Crystallography (MX)