Madiraju, Murty V.V.S., Ph.D.
Mycobacterium tuberculosis proliferation mechanisms, Replication Initiation and Cell Cycle.
We are interested in understanding the proliferation mechanisms of Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis. Mtb is also the leading cause of morbidity and mortality in AIDS patients. It is known that following infection, Mtb frequently enters a latent state for extended periods and subsequently, under appropriate conditions or following immune suppression, revives, multiplies and causes diesase. Regulation of DNA replication is one of the important factors affecting Mtb ability to enter into and exit from latency. The development of novel therapeutic agents to control Mtb infections in HIV infected patients as well as other individuals is severely hindered by our limited understanding of the initiation and regulation of Mtb DNA replication and its coordination with other events in cell cycle. DNA replication is initiated at a unique site on the chromosome called oriC and is believed to occur when the initiator protein DnaA interacts with oriC and recognizes the DnaA protein reconginition sequences called DnaA-boxes to catalyze the formation of initiation complex. It is largely unknown how this process is regulated at different stages of growth and infection.
Mtb operates serveral regulatory networks for its optimal survival upon infection, and one such regulatory network is histidine-aspartate two component regulatory signal transduction system (2CRS). MtrAB is one of the essential 2CRS that includes a membrane bound sensor kinase MtrB and cytosolic response regulator MtrA. In response to changes in environmental stimuli, MtrB undergoes autophosphorylation and then transfers its phosphate to MtrA for modualting gene expression. Recent work in our laboratory revealed that dnaA promoter and oriC are MtrA targets. While these studies signal an intimate connection between the two essential pathways: DnaA mediated oriC replication and MtrAB 2CRS, it is largely unknown how oriC replication is regulated by MtrA response regulator and its phosphorylation status, specifically during active and persistent growth states. Our current research explores this exciting area of research using a combination of genetic, molecular biological and biochemical approaches. Detailed knowledge on Mtb oriC activation mechanisms both during active growth and exit from latent state is an essential prerequisite for the development of drugs to inhibit the initiation of replication and thereby prevent the development of potentially lethal infections of Mtb.
We recently defined the MtrA regulon by ChIP-Seq, and are now focussing on dissecting the roles of MtrAB signal transduction pathway on Mtb proliferation upon infection.
Selected Papers and Abstracts:
- Plocinski, P, Arora, N, Sarva, K, Blasczczyk, E.,Qin, H., Das, N., Plocinska, R., Ziolkiewic, M.m Dziadek, J.,Kiran, M.,Cross, T.A., Madiraju, M.V., and M. Rajagoapaln. Mycobacterium tuberculosis CwsA interacts with CrgA and Wag31 and the CrgA-CwsA complex is involved in PG synthesis and cell shape determination. J Bacteriol. 2012 Dec;194(23):6398-409.
- Plocinska R, Purushotham G, Sarva K, Vadrevu IS, Pandeeti EV, Arora N, Plocinski P, Madiraju MV, Rajagopalan M. Septal localization of Mycobacterium tuberculosis MtrB sensor kinase promotes MtrA regulon expression. J Biol Chem. 2012 Jul 6;287(28):23887-99.
- Madiraju M, Madiraju SC, Yamamoto K, Greendyke R, Rajagopalan M. Replacement of Mycobacterium smegmatis dnaA gene by Mycobacterium tuberculosis homolog results in temperature sensitivity. Tuberculosis (Edinb). 2011 Dec;91 Suppl 1:S136-41.
- Vadrevu IS, Lofton H, Sarva K, Blasczyk E, Plocinska R, Chinnaswamy J, Madiraju M, Rajagopalan M. ChiZ levels modulate cell division process in mycobacteria. Tuberculosis (Edinb). 2011 Dec;91 Suppl 1:S128-35.
- Maloney E, Madiraju SC, Rajagopalan M, Madiraju M. Localization of acidic phospholipid cardiolipin and DnaA in mycobacteria. Tuberculosis (Edinb). 2011 Dec; 91 Suppl 1:S150-5.
- Plocinski P, Ziolkiewicz M, Kiran M, Vadrevu SI, Nguyen HB, Hugonnet J, Veckerle C, Arthur M, Dziadek J, Cross TA, Madiraju M, Rajagopalan M. Characterization of CrgA, a New Partner of the Mycobacterium tuberculosis Peptidoglycan Polymerization Complexes. J Bacteriol. 2011 Jul;193(13):3246-56.
- Al Zayer M, Stankowska D, Dziedzic R, Sarva K, Madiraju MV, Rajagopalan M. Mycobacterium tuberculosis mtrA merodiploid strains with point mutations in the signal-receiving domain of MtrA exhibit growth defects in nutrient broth. Plasmid. 2011 May;65(3):210-8.
- Maloney E, Lun S, Stankowska D, Guo H, Rajagoapalan M, Bishai WR, Madiraju MV. Alterations in phospholipid catabolism in Mycobacterium tuberculosis lysX mutant. Front Microbiol. 2011 Feb 11; 2:19.
- Roberts G, Vadrevu IS, Madiraju MV, Parish T. Control of CydB and GltA1 Expression by the SenX3 RegX3 Two Component Regulatory System of Mycobacterium tuberculosis. PLoS One. 2011; 6(6):e21090.
- Dziedzic R, Kiran M, Plocinski P, Ziolkiewicz M, Brzostek A, Moomey M, Vadrevu IS, Dziadek J, Madiraju M, Rajagopalan M. Mycobacterium tuberculosis ClpX interacts with FtsZ and interferes with FtsZ assembly. PLoS One. 2010 Jul 6;5(7):e11058.
- Rajagopalan M, Dziedzic R, Al Zayer M, Stankowska D, Ouimet MC, Bastedo DP, Marczynski GT, Madiraju MV. Mycobacterium tuberculosis origin of replication and the promoter for immunodominant secreted antigen 85B are the targets of MtrA, the essential response regulator. J Biol Chem. 2010 May 21;285(21):15816-27.
- Kiran M, Chauhan A, Dziedzic R, Maloney E, Mukherji SK, Madiraju M, Rajagopalan M. Mycobacterium tuberculosis ftsH expression in response to stress and viability. Tuberculosis (Edinb). 2009 Dec;89 Suppl 1:S70-3.
- Maloney E, Madiraju M, Rajagopalan M. Overproduction and localization of Mycobacterium tuberculosis ParA and ParB proteins. Tuberculosis (Edinb). 2009 Dec;89 Suppl 1:S65-9.
- Kiran M, Maloney E, Lofton H, Chauhan A, Jensen R, Dziedzic R, Madiraju M, Rajagopalan M. Mycobacterium tuberculosis ftsZ expression and minimal promoter activity. Tuberculosis (Edinb). 2009 Dec;89 Suppl 1:S60-4.
- Maloney E, Stankowska D, Zhang J, Fol M, Cheng QJ, Lun S, Bishai WR, Rajagopalan M, Chatterjee D, Madiraju MV. The two-domain LysX protein of Mycobacterium tuberculosis is required for production of lysinylated phosphatidylglycerol and resistance to cationic antimicrobial peptides. PLoS Pathog. 2009 Jul;5(7):e1000534.
- Nair N, Dziedzic R, Greendyke R, Muniruzzaman S, Rajagopalan M, Madiraju MV. Synchronous replication initiation in novel Mycobacterium tuberculosis dnaA cold-sensitive mutants. Mol Microbiol. 2009 Jan;71(2):291-304. Epub 2008 Nov 14.