A Mycobacterium avium subsp. paratuberculosis Predicted Serine Protease Is Associated with Acid Stress and Intraphagosomal Survival.
The ability to maintain intra-cellular pH is crucial for bacteria and other microbes to survive in diverse environments, particularly those that undergo fluctuations in pH. Mechanisms of acid resistance remain poorly understood in mycobacteria. Although, studies investigating acid stress in M. tuberculosis are gaining traction, few center on Mycobacterium avium subsp. paratuberculosis (MAP), the etiological agent of chronic enteritis in ruminants. We identified a MAP acid stress response network involved in macrophage infection. The central node of this network was MAP0403, a predicted serine protease that shared an 86% amino acid identity with MarP in M. tuberculosis. Previous studies confirmed MarP as a serine protease integral to maintaining intra-bacterial pH and survival in acid in vitro and in vivo. We show that MAP0403 is upregulated in infected macrophages and MAC-T cells that coincided with phagosome acidification. Treatment of mammalian cells with bafilomcyin A1, a potent inhibitor of phagosomal vATPases, diminished MAP0403 transcription. MAP0403 expression was also noted in acidic medium. A surrogate host, M. smegmatis mc(2) 155, was designed to express MAP0403 and when exposed to either macrophages or in vitro acid stress had increased bacterial cell viability, which corresponds to maintenance of intra-bacterial pH in acidic (pH = 5) conditions, compared to the parent strain. These data suggest that MAP0403 may be the equivalent of MarP in MAP. Future studies confirming MAP0403 as a serine protease and exploring its structure and possible substrates are warranted.
Division of Infectious Diseases, Brigham and Women's Hospital, University of Minnesota Boston, MA, USA.
Abirami
A
Kugadas
Department of Veterinary and Biomedical Science, University of Minnesota Saint Paul, MN, USA.
Elise A
EA
Lamont
United States Department of Agriculture, National Animal Disease Center, Agricultural Research Service Ames, IA, USA.
John P
JP
Bannantine
Department of Veterinary Population Medicine, University of Minnesota Saint Paul, MN, USA.
Fernanda M
FM
Shoyama
Department of Veterinary Population Medicine, University of Minnesota Saint Paul, MN, USA.
Evan
E
Brenner
Institute for Environmental Health Lake Forest Park, WA, USA.
Harish K
HK
Janagama
Department of Veterinary and Biomedical Science, University of MinnesotaSaint Paul, MN, USA; Department of Veterinary Population Medicine, University of MinnesotaSaint Paul, MN, USA.
Srinand
S
Sreevatsan
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D002460:Cell Line; D004269:DNA, Bacterial; D018942:Macrolides / Q000494:pharmacology; D008264:Macrophages / Q000382:microbiology; D050296:Microbial Viability; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D016927:Mycobacterium avium subsp. paratuberculosis / Q000187:drug effects* / Q000201:enzymology* / Q000254:growth & development / Q000472:pathogenicity; D010283:Paratuberculosis / Q000382:microbiology; D010588:Phagosomes / Q000382:microbiology; D012329:RNA, Bacterial / Q000235:genetics; D017384:Sequence Deletion; D057057:Serine Proteases / Q000378:metabolism*; D013312:Stress, Physiological / Q000502:physiology*; D059467:Transcriptome
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D018942:Macrolides; D008869:Microtubule-Associated Proteins; D012329:RNA, Bacterial; C040929:bafilomycin A1; D057057:Serine Proteases
Johne's disease; Mycobacterium avium subsp. paratuberculosis; acid; intrabacterial pH; macrophage; phagosome; serine protease