Characterization and expression of secA in Mycobacterium avium.
Mycobacterium avium is both a pathogen that infects several hosts such as humans, pigs, and birds, as well as a microorganism that is encountered in environmental sources (soil and water). Protein secretion by the bacterium is likely to influence its ability to overcome adverse and competitive conditions both within or outside the host. Using a combination of cloning and information available in the databank, we characterized the secA gene from M. avium, encoding for a major preprotein translocase subunit associated with the secretion system of prokaryotics. In addition, we cloned the secA promoter sequence in a reporter construct upstream of a promoterless gfp. It was determined that the secA of M. avium shares large homology with the secA of Mycobacterium tuberculosis but not with secA of Mycobacterium leprae. secA expression was determined to be greater at logarithmic growth phase although it was also expressed at low levels during the stationary phase. secA expression was also observed when the bacteria were incubated in water as well as within human monocyte-derived macrophages and in conditions that are associated with biofilm formation. Future evaluation of the sec pathway in M. avium might provide important information about secreted proteins that are required for survival in different environments.
Limia
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Kuzell Institute for Arthritis and Infectious Diseases, California Pacific Medical Center Research Institute, 2200 Webster Street, Suite 305, San Francisco, CA 94115, USA.
Sangari
F J
FJ
Wagner
D
D
Bermudez
L E
LE
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D018441:Biofilms / Q000254:growth & development; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics*; D003001:Cloning, Molecular; D003470:Culture Media; D029968:Escherichia coli Proteins; D006801:Humans; D008264:Macrophages / Q000382:microbiology; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D009162:Mycobacterium avium / Q000737:chemistry / Q000235:genetics* / Q000254:growth & development; D011401:Promoter Regions, Genetic; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D014867:Water
D001426:Bacterial Proteins; D002352:Carrier Proteins; D003470:Culture Media; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D000069816:SEC Translocation Channels; D014867:Water; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins