Centre for Cellular and Molecular Biology

About: Centre for Cellular and Molecular Biology is a facility organization based out in Hyderabad, India. It is known for research contribution in the topics: Population & Gene. The organization has 2439 authors who have published 3193 publications receiving 97833 citations.

Nonprocessive [2 + 2]e- off-loading reductase domains from mycobacterial nonribosomal peptide synthetases

Abstract: In mycobacteria, polyketide synthases and nonribosomal peptide synthetases (NRPSs) produce complex lipidic metabolites by using a thio-template mechanism of catalysis. In this study, we demonstrate that off-loading reductase (R) domain of mycobacterial NRPSs performs two consecutive [2 + 2]e- reductions to release thioester-bound lipopeptides as corresponding alcohols, using a nonprocessive mechanism of catalysis. The first crystal structure of an R domain from Mycobacterium tuberculosis NRPS provides strong support to this mechanistic model and suggests that the displacement of intermediate would be required for cofactor recycling. We show that 4e- reductases produce alcohols through a committed aldehyde intermediate, and the reduction of this intermediate is at least 10 times more efficient than the thioester-substrate. Structural and biochemical studies also provide evidence for the conformational changes associated with the reductive cycle. Further, we show that the large substrate-binding pocket with a hydrophobic platform accounts for the remarkable substrate promiscuity of these domains. Our studies present an elegant example of the recruitment of a canonical short-chain dehydrogenase/reductase family member as an off-loading domain in the context of assembly-line enzymology.

yciM is an essential gene required for regulation of lipopolysaccharide synthesis in Escherichia coli

Abstract: The outer membrane of Gram-negative bacteria is an asymmetric lipid bilayer consisting of an essential glycolipid lipopolysaccharide (LPS) in its outer leaflet and phospholipids in the inner leaflet. Here, we show that yciM, a gene encoding a tetratricopeptide repeat protein of unknown function, modulates LPS levels by negatively regulating the biosynthesis of lipid A, an essential constituent of LPS. Inactivation of yciM resulted in high LPS levels and cell death in Escherichia coli; recessive mutations in lpxA, lpxC or lpxD that lower the synthesis of lipid A, or a gain of function mutation in fabZ that increases the formation of membrane phospholipids, alleviated the yciM mutant phenotypes. A modest increase in YciM led to significant reduction of LPS and increased sensitivity to hydrophobic antibiotics. YciM was shown to regulate LPS by altering LpxC, an enzyme that catalyses the first committed step of lipid A biosynthesis. Regulation of LpxC by YciM was contingent on the presence of FtsH, an essential membrane-anchored protease known to degrade LpxC, suggesting that FtsH and YciM act in concert to regulate synthesis of lipid A. In summary, this study demonstrates an essential role for YciM in regulation of LPS biosynthesis in E. coli.

Molecular characterization of some Indian Basmati and other elite rice genotypes using fluorescent-AFLP

Abstract: Cultivated rice is a high-volume, low-value cereal crop providing staple food to more than 50% of the world populace. A small group of rice cultivars, traditionally produced on the Indo-Gangetic plains and popularly known as Basmati, have exquisite quality grain characteristics and are a prized commercial commodity. Efforts to improve the yield potential of Basmati have led to the development of several crossbred Basmati-like cultivars. In this study we have analysed the genetic diversity and interrelationships among 33 rice genotypes consisting of the traditional Basmati, improved Basmati-like genotypes developed in India and elsewhere, American long-grain rice and a few non-aromatic rice using a DNA marker-based approach – fluorescent-amplified fragment length polymorphism (f-AFLP). Using a set of nine primer-pairs we scored a total of 10,672 data points over all of the genotypes in the size range of 75–500 bp. The scored data points corresponded to a total of 501 AFLP markers (putative loci/genome landmarks) of which 327 markers (65%) were polymorphic. The f-AFLP marker data, which were analysed using different clustering algorithms and principal component analysis, indicate that: (1) considerable genetic variability exists in the analysed genotypes; (2) traditional Basmati cultivars could be distinctly separated from the crossbred Basmati-like genotypes as well as from the non-aromatic rice; (3) the crossbred Basmati-like cultivars from the subcontinent and elsewhere are genetically very distinct; (4) f-AFLP-based clustering, in general, conforms to the putative pedigree of the improved genotypes. Moreover, analysis to ascertain the scope of AFLP as a technique suggests that the polymorphism revealed by three selective primer-pair combinations is sufficient to obtain reliable estimates of genetic diversity for the type of material used in this study. However, its utility to identify group-specific DNA markers was discounted due to a low frequency of observed group-specific discrete markers.

Mitochondrial DNA coding region sequences support the phylogenetic distinction of two Indian wolf species

Abstract: Two small endangered populations of Indian wolves were recently shown to be distant from other wolf and dog mtDNA lineages characterized so far. None of the inner branches in the tree of canid species based on partial hypervariable D-loop sequences were, however, statistically supported by the data raising the question whether the two Indian wolf lineages represent two new species, occupying an intermediate position between Canis latrans and C. lupus or have diverged from the sub-species of C. lupus due to isolation and drift. Here we report complete D-loop, cytochrome b, and 16S rRNA sequences data for 23 additional wolves from India analysed in the context of other canid species. Extended analyses of D-loop data and partial sequences of 16S rRNA showed highly reticulated pattern and were unable to resolve unambiguously the phylogenetic relationship of Indian wolves among other canid species. The phylogenetic reconstructions of cytochrome b sequences, however gave significant statistical support for the inner branches supporting genetic distinction of the two Indian wolf lineages within themselves as well as from all other wolves of the world, including individuals belonging to subspecies C. lupus chanco and C. lupus pallipes to which the two Indian wolf populations have been traditionally assigned. Their genetic differentiation relative to worldwide variation of wolves supports the suggestion to treat them as separate wolf species, C. himalayensis and C. indica.