Quantitative Protein Profiling of Chlamydia trachomatis Growth Forms Reveals Defense Strategies Against Tryptophan Starvation

TY - JOUR

T1 - Quantitative Protein Profiling of Chlamydia trachomatis Growth Forms Reveals Defense Strategies Against Tryptophan Starvation

AU - Østergaard, Ole

AU - Follmann, Frank

AU - Olsen, Anja W

AU - Heegaard, Niels H

AU - Andersen, Peter

AU - Rosenkrands, Ida

N1 - © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

PY - 2016/12

Y1 - 2016/12

N2 - Chlamydia trachomatis is one of the most common sexually transmitted bacterial pathogens in humans. The infection is often asymptomatic and can lead to chronic manifestations. The infectious elementary body and the replicating reticulate body are the two growth forms in the normal developmental cycle. Under the influence of interferon-γ, the normal cycle is disrupted because of tryptophan degradation, leading to a third persistent form, the aberrant reticulate body.For the genital strain C. trachomatis D/UW-3/CX we established a quantitative, label-free proteomic approach, and identified in total 655 out of 903 (73%) predicted proteins, allowing the first quantitative comparison of all three growth forms. Inclusion membrane proteins and proteins involved in translation were more abundant in the reticulate body (RB)1 and aberrant reticulate body (ARB) forms, whereas proteins of the type III Secretion System and the cell envelope were more abundant in the elementary body (EB) form, reflecting the need for these proteins to establish infection and for host interactions.In the interferon-γ induced ARB proteome, the tryptophan synthase subunits were identified as biomarkers with a strong increase from less than 0.05% to 9% of the total protein content, reflecting an inherent defense strategy for the pathogen to escape interferon-γ mediated immune pressure. Furthermore, the total tryptophan content in the ARB form was 1.9-fold lower compared with the EB form, and we demonstrate that modulation of the protein repertoire toward lower abundance of proteins with high tryptophan content, is a mechanism which contributes to establish and maintain chlamydial persistence. Thus, quantitative proteomics provides insights in the Chlamydia defense mechanisms to escape interferon-γ mediated immune pressure.

AB - Chlamydia trachomatis is one of the most common sexually transmitted bacterial pathogens in humans. The infection is often asymptomatic and can lead to chronic manifestations. The infectious elementary body and the replicating reticulate body are the two growth forms in the normal developmental cycle. Under the influence of interferon-γ, the normal cycle is disrupted because of tryptophan degradation, leading to a third persistent form, the aberrant reticulate body.For the genital strain C. trachomatis D/UW-3/CX we established a quantitative, label-free proteomic approach, and identified in total 655 out of 903 (73%) predicted proteins, allowing the first quantitative comparison of all three growth forms. Inclusion membrane proteins and proteins involved in translation were more abundant in the reticulate body (RB)1 and aberrant reticulate body (ARB) forms, whereas proteins of the type III Secretion System and the cell envelope were more abundant in the elementary body (EB) form, reflecting the need for these proteins to establish infection and for host interactions.In the interferon-γ induced ARB proteome, the tryptophan synthase subunits were identified as biomarkers with a strong increase from less than 0.05% to 9% of the total protein content, reflecting an inherent defense strategy for the pathogen to escape interferon-γ mediated immune pressure. Furthermore, the total tryptophan content in the ARB form was 1.9-fold lower compared with the EB form, and we demonstrate that modulation of the protein repertoire toward lower abundance of proteins with high tryptophan content, is a mechanism which contributes to establish and maintain chlamydial persistence. Thus, quantitative proteomics provides insights in the Chlamydia defense mechanisms to escape interferon-γ mediated immune pressure.

KW - Bacterial Proteins/metabolism

KW - Chlamydia trachomatis/drug effects

KW - Chromatography, Liquid

KW - Gene Expression Regulation, Bacterial/drug effects

KW - HeLa Cells

KW - Humans

KW - Interferon-gamma/pharmacology

KW - Proteomics/methods

KW - Tandem Mass Spectrometry

KW - Tryptophan/metabolism

U2 - 10.1074/mcp.m116.061986

DO - 10.1074/mcp.m116.061986

M3 - Journal article

C2 - 27784728

SN - 1535-9476

VL - 15

SP - 3540

EP - 3550

JO - Molecular and Cellular Proteomics

JF - Molecular and Cellular Proteomics

IS - 12

ER -