The long term goals of this proposal are to understand the control of bacterial DNA replication and the connections between replication and gene expression. Cell growth and propagation require duplication and segregation of chromosomal DNA. Cells have multiple mechanisms for regulating the initiation of replication and many have regulatory responses to perturbations in replication, often called checkpoints, which control cell cycle progression. Coupling gene expression and cell cycle progression to chromosome replication and integrity helps prevent the generation of cells with defective chromosomes. The coordination of genome duplication with cell cycle progression is also important for cellular differentiation and preventing uncontrolled cell growth. Many diseases, including cancers, result from aberrant regulation of replication and cell growth. In addition, microbial pathogenesis often depends on normal bacterial replication and growth in the host. This proposal focuses on several aspects of chromosome dynamics and gene expression in the Gram- positive bacterium Bacillus subtilis. We will use a variety of approaches and methodologies, both in vivo and in vitro, to characterize genes controlled in response to replication fork arrest, the role of DnaA, the replication initiator protein, in the transcriptional response to replication fork arrest, and the control of replication initiation and assembly of the replisome at an origin of replication in vivo. The fundamental principles and mechanisms controlling these processes are easily studied in B. subtilis using a combination of cell biological, genetic, molecular, physiological, biochemical, and bioinformatic approaches. Because many of the proteins involved in these processes are highly conserved, insights gained from our work with this relatively simple, experimentally accessible microbe, are likely to provide information regarding similar processes and homologous proteins in a wide variety of organisms, including many of the important Gram-positive pathogens. Learning more about the essential mechanisms governing chromosome replication and its effects on gene expression could lead to the identification of targets for the development of new antibiotics.
Many diseases, including cancers, result from aberrant regulation of replication and cell growth and microbial pathogenesis often depends on normal bacterial replication and growth, making these processes potentially useful antibiotic targets. This project investigates several conserved aspects of replication control and cellular responses to altered replication in the bacterium Bacillus subtilis, a harmless yet useful organism that is representative of several bacterial species that cause serious human disease, including Bacillus anthracis, Clostridium difficile, Enterococcus faecalis, Staphylococcus aureus, and Streptococcus pneumoniae.
|Merrikh, Houra; Machon, Cristina; Grainger, William H et al. (2011) Co-directional replication-transcription conflicts lead to replication restart. Nature 470:554-7|
|Rahn-Lee, Lilah; Merrikh, Houra; Grossman, Alan D et al. (2011) The sporulation protein SirA inhibits the binding of DnaA to the origin of replication by contacting a patch of clustered amino acids. J Bacteriol 193:1302-7|
|Merrikh, Houra; Grossman, Alan D (2011) Control of the replication initiator DnaA by an anti-cooperativity factor. Mol Microbiol 82:434-46|
|Smits, Wiep Klaas; Merrikh, Houra; Bonilla, Carla Yaneth et al. (2011) Primosomal proteins DnaD and DnaB are recruited to chromosomal regions bound by DnaA in Bacillus subtilis. J Bacteriol 193:640-8|
|Marston, Farhat Y; Grainger, William H; Smits, Wiep Klaas et al. (2010) When simple sequence comparison fails: the cryptic case of the shared domains of the bacterial replication initiation proteins DnaB and DnaD. Nucleic Acids Res 38:6930-42|
|Smits, Wiep Klaas; Goranov, Alexi I; Grossman, Alan D (2010) Ordered association of helicase loader proteins with the Bacillus subtilis origin of replication in vivo. Mol Microbiol 75:452-61|
|Smits, Wiep Klaas; Grossman, Alan D (2010) The transcriptional regulator Rok binds A+T-rich DNA and is involved in repression of a mobile genetic element in Bacillus subtilis. PLoS Genet 6:e1001207|
|Goranov, Alexi I; Breier, Adam M; Merrikh, Houra et al. (2009) YabA of Bacillus subtilis controls DnaA-mediated replication initiation but not the transcriptional response to replication stress. Mol Microbiol 74:454-66|
|Rokop, Megan E; Grossman, Alan D (2009) Intragenic and extragenic suppressors of temperature sensitive mutations in the replication initiation genes dnaD and dnaB of Bacillus subtilis. PLoS One 4:e6774|
|Simmons, Lyle A; Goranov, Alexi I; Kobayashi, Hajime et al. (2009) Comparison of responses to double-strand breaks between Escherichia coli and Bacillus subtilis reveals different requirements for SOS induction. J Bacteriol 191:1152-61|
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