Molecular insights into the structure, function, and stability of the DNA polymerase processivity factor from Mycobacterium tuberculosis.

Emergence of drug resistance in Mycobacterium tuberculosis (Mtb) calls for newer drugs and drug targets. Essential proteins such as DNA polymerase (DNAP) processivity factor, also called sliding clamp (DnaN), are indispensable for bacterial survival, and are excellent drug targets. Here, we constructed a dnaN-conditional knockout in Mycobacterium smegmatis (MsmΔdnaN) and were able to successfully complement it with Mtb DnaN (DnaN).

Mycofactocin is essential for the establishment of methylotrophy in Mycobacterium smegmatis.

Mycobacterium smegmatis possesses (N,N-dimethyl-4-nitrosoaniline)-dependent (NDMA) methanol dehydrogenase (Mno) to establish methylotrophy by utilizing methanol as the source of both carbon and energy. In this study, we show that Mno forms decamer and has NADPH as the bound cofactor. Interestingly, Mno uses NDMA and not NADP as an electron acceptor in in vitro reactions.

Identification and Characterization of an Inside-Out Folding Intermediate of T4 Phage Sliding Clamp.

Protein folding process involves formation of transiently occurring intermediates that are difficult to isolate and characterize. It is both necessary and interesting to characterize the structural conformations adopted by these intermediates, also called molten globules (MG), to understand protein folding. Here, we investigated the equilibrium (un)folding intermediate state of T4 phage gene product 45 (gp45, also known as DNA polymerase processivity factor or sliding clamp) obtained during chemical denaturation.

Structural plasticity of T4 transcription co-activator gp33 revealed by a protease-resistant unfolded state.

Gene 33 protein (gp33) is a transcriptional coactivator for late genes of the T4 bacteriophage. gp33 possesses a 5-helix bundle core, with unstructured N- and C-terminal regions that account for >50% of the protein sequence. It plays a unique role of interacting with host RNA polymerase, couples transcription with DNA replication, and plays the dual function as repressor and co-activator in phage transcription.

Novel method to rapidly and efficiently lyse Escherichia coli for the isolation of recombinant protein.

Rapid and high-throughput protein purification methods are required to explore structure and function of several uncharacterized proteins. Isolation of recombinant protein expressed in Escherichia coli strain BL21 (DE3) depends largely on the efficient and speedy bacterial cell lysis, which is considered as the bottleneck during protein purification. Cells are usually lysed by either sonication or high pressure homogenization, both of which are slow, require special equipment, lead to heat generation, and may result in loss of protein's biological activity.

On the domains of T4 phage sliding clamp gp45: An intermolecular crosstalk governs structural stability and biological activity.

Background: DNA polymerase processivity factors are ubiquitously present in all living organisms. Notwithstanding their high significance, the molecular details of clamps pertaining to the factors contributing to their stability are presently lacking. The bacteriophage T4 sliding clamp gp45 forms a homotrimer that besides being involved in DNA replication, moonlights as a transcription factor.

Modulation of domain-domain interaction and protein function by a charged linker: a case study of mycobacteriophage D29 endolysin.

Phage-encoded cell wall peptidoglycan hydrolyzing enzymes, called endolysins, are essential for efficient release of virions from bacteria, and show species-specific killing of the host. We have demonstrated previously that the interaction between N-terminal catalytic and C-terminal cell wall binding domains of mycobacteriophage D29 endolysin makes the enzyme inactive in Escherichiacoli. Here, we demonstrate that such interaction occurs intramolecularly and is facilitated by a charged linker that connects the two domains.

Evidence of a conserved intrinsically disordered region in the C-terminus of the stringent response protein Rel from mycobacteria.

The RelA/SpoT enzyme produces (p)ppGpp that helps the bacterium survive during stress. The domains present in it are interspersed with connecting linkers whose functions have been poorly elucidated. We rationally analyzed the sequence and structural property of the regulatory C-terminal region in the Rel family of proteins and report the presence of an intrinsically disordered region between two successive domains in this region that are separated by a defined amino acid sequence length.

Molecular dissection of phage endolysin: an interdomain interaction confers host specificity in Lysin A of Mycobacterium phage D29.

Mycobacterium tuberculosis has always been recognized as one of the most successful pathogens. Bacteriophages that attack and kill mycobacteria offer an alternate mechanism for the curtailment of this bacterium. Upon infection, mycobacteriophages produce lysins that catalyze cell wall peptidoglycan hydrolysis and mycolic acid layer breakdown of the host resulting in bacterial cell rupture and virus release.