The genomes of thirteen rickettsial species have been sequenced providing many insights into their biology; however, the molecular basis of protein secretion involved in rickettsial pathogenesis remains an important area of research for rickettsiae. The annotation of published rickettsial genome sequences and our laboratory work indicate that Rickettsia possess a Sec protein secretion pathway as well as Type IV secretion system.
The aim of my research is focused on secreted proteins of rickettsiae. The rationale for targeting secreted proteins is based on the hypothesis that secreted proteins are involved in many essential cellular processes including adherence and growth; as well as involved in the immune response. My current effort is molecular and functional characterization of extracytoplasmic secreted proteins with particular emphasis on their role for rickettsial infection, intracellular growth and damage to host cells.
Ammerman NC, Rahman MS and Azad AF. Characterization of Sec translocon-dependent extracytoplasmic proteins of Rickettsia typhi. J Bacteriol. 2008, [Epub ahead of print]. PMID: 18641131.
Dreher-Lesnick SM, Ceraul SM, Rahman MS and Azad AF. Genome-wide screen for temperature-regulated genes of the obligate intracellular bacterium, Rickettsia typhi. BMC Microbiol. 2008, 8:61. PMID: 18412961.
Gillespie JJ, Beier MS, Rahman MS, Ammerman NC, Shallom JM, Purkayastha A, Sobral BS and Azad AF. Plasmids and rickettsial evolution: insight from Rickettsia felis. PLoS ONE. 2007 2(3):e266. PMID: 17342200.
Ceraul SM, Dreher-Lesnick SM, Gillespie JJ, Rahman MS and Azad AF. New tick defensin isoform and antimicrobial gene expression in response to Rickettsia montanensis challenge. Infect Immun. 2007, 75(4):1973-83. PMID: 17261604.
Rahman MS, Ceraul SM, Dreher-Lesnick SM, Beier MS and Azad AF. The lspA gene, encoding the type II signal peptidase of Rickettsia typhi: transcriptional and functional analysis. J Bacteriol. 2007, 189(2):336-41. PMID: 17098907.
Simser JA, Rahman MS, Dreher-Lesnick SM and Azad AF. A novel and naturally occurring transposon, ISRpe1 in the Rickettsia peacockii genome disrupting the rickA gene involved in actin-based motility. Mol Microbiol. 2005, 58(1):71-9. PMID: 16164550.
Rahman MS, Simser JA, Macaluso KR and Azad AF. Functional analysis of secA homologues from rickettsiae. Microbiology. 2005, 151(Pt 2):589-96. PMID: 15699207.
Rahman MS, Simser JA, Macaluso KR and Azad AF. Molecular and functional analysis of the lepB gene, encoding a type I signal peptidase from Rickettsia rickettsii and Rickettsia typhi. J Bacteriol. 2003, 185(15):4578-84. PMID: 12867468.
Radulovic S, Rahman MS, Beier MS and Azad AF. Molecular and functional analysis of the Rickettsia typhi groESL operon. Gene. 2002, 18;298(1):41-8. PMID: 12406574.