Amitava Bandhu

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The protein kinase Mec1 (ATR ortholog) and its partner Ddc2 (ATRIP ortholog) play a key role in DNA damage checkpoint responses in budding yeast. Previous studies have established the model in which Ddc1, a subunit of the checkpoint clamp, and Dpb11, related to TopBP1, activate Mec1 directly and control DNA damage checkpoint responses at G1 and G2/M. In(More)
The repressor protein and cognate operator DNA of any temperate Staphylococcus aureus phage have not been investigated in depth, despite having the potential to enrich the molecular biology of the staphylococcal system. In the present study, using the extremely pure repressor of temperate Staphylococcus aureus phage phi11 (CI), we demonstrate that CI is(More)
Of the three cold shock proteins expressed by Staphylococcus aureus, CspC is induced poorly by cold but strongly by various antibiotics and toxic chemicals. Using a purified CspC, here we demonstrate that it exists as a monomer in solution, possesses primarily β-sheets, and bears substantial structural similarity with other bacterial Csps. Aggregation of(More)
The primary sigma factor (sigma(A)) of Staphylococcus aureus, a potential drug target, was little investigated at the structural level. Using an N-terminal histidine-tagged sigma(A) (His-sigma(A)), here we have demonstrated that it exits as a monomer in solution, possesses multiple domains, harbors primarily alpha-helix and efficiently binds to a S. aureus(More)
Previously, the repressor protein of mycobacteriophage L1 bound to two operator DNAs with dissimilar affinity. Surprisingly, the putative operator consensus sequence, 5'GGTGGa/cTGTCAAG, lacks the dyad symmetry reported for the repressor binding operators of lambda and related phages. To gain insight into the structure of the L1 repressor-asymmetric operator(More)
Lysogenic mode of life cycle of a temperate bacteriophage is generally maintained by a protein called 'repressor'. Repressor proteins of temperate lambdoid phages bind to a few symmetric operator DNAs in order to regulate their gene expression. In contrast, repressor molecules of temperate mycobacteriophages and some other phages bind to multiple asymmetric(More)
FKBP22, a protein expressed by Escherichia coli, possesses PPIase (peptidyl-prolyl cis-trans isomerase) activity, binds FK506 (an immunosuppressive drug), and shares homology with Legionella Mip (a virulence factor) and its related proteins. To understand the domain structure and the folding-unfolding mechanism of Mip-like proteins, we investigated a(More)
The temperate Staphylococcus aureus phage Phi11 harbors cI and cro repressor genes similar to those of lambdoid phages. Using extremely pure Phi11 Cro (the product of the Phi11 cro gene) we demonstrated that this protein possesses a single domain structure, forms dimers in solution at micromolar concentrations and maintains a largely alpha-helical structure(More)
To determine the factors influencing the binding of L1 repressor to its cognate operator DNA, several gel shift as well as bioinformatic analyses have been carried out. The data show that time, temperature, salt, and pH each greatly affect the binding. In order to achieve optimum operator binding of L1 repressor in Tris buffer, the minimum requirements of(More)
A mycobacteriophage-specific repressor with the enhanced operator DNA binding activity at 32°C and no activity at 42°C has not been generated yet though it has potential in developing a temperature-controlled expression vector for mycobacterial system. To create such an invaluable repressor, here we have characterized four substitution mutants of(More)