Original Article Acid stress response of a mycobacterial proteome: insight from a gene ontology analysis
Bryan A.P. Roxas, Qingbo Li
Center for Pharmaceutical Biotechnology, College of Pharmacy, University of Illinois at Chicago, Chicago, IL 60607, USA; Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA; Current address: Department of Veterinary Science and Microbiology, University of Arizona, Tucson, AZ 85721, USA.
Received October 7, 2009; accepted November 5, 2009; available online November 10, 2009
Abstract: Acidity in vesicles of macrophages is a general signal that bacteria respond to during infection. Mycobacteria are particularly capable of resisting the acidification in macrophages that engulf the bacteria. In this work, we used label-free quantitative proteomics to study the Mycobacterium smegmatis proteome under acid stress so as to gain an insight into the acidic adaptation in mycobacteria. We quantified 1032 proteins. With a 3-fold change threshold, 20 and 52 proteins were found regulated at false discovery rates of 5% and 14% respectively. We performed a systems analysis based on gene ontology for the global proteome expression profile. We found that the most significant changes induced by the acid stress include a downregulation of transmembrane transporter activity and an upregulation of enzymes involved in fatty acid metabolism. The results suggest that reduced transmembrane transport and increased fatty acid metabolism probably contribute to or associate with acid tolerance in mycobacteria. (IJCEM910001).
Key words: Mycobacterium smegmatis, acid stress, label-free proteomics, gene ontology, systems biology, membrane transport
Address all correspondence to: Qingbo Li, PhD Center for Pharmaceutical Biotechnology College of Pharmacy, University of Illinois at Chicago Chicago, IL 60607, USA; Department of Microbiology and Immunology College of Medicine, University of Illinois at Chicago Chicago, IL 60612, USA; Tel: 312-413-9301; Fax: 312-413-9303 E-mail: qkli@uic.edu