Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sophisticated biochemical networks allow organisms such as bacteria and insects to switch from very rapid growth and development in ideal environments to dormancy during severely unfavorable conditions. These switches may be accompanied by abrupt changes in oxidation/reduction involving reactive oxygen species (ROS). ROS have the potential of damaging nucleic acids, proteins, and membranes. In Escherichia coli, certain genetically regulated circuits (regulons) turn on synthesis of anti-oxidant enzymes to protect against distinct ROS excesses (superoxide, hydrogen peroxide, organic or lipid peroxides, etc.). As examples, the soxRS regulon controls synthesis of Mn-superoxide dismutase, oxyR controls catalase HPI, rpoS positively regulates HPII, and fur regulates several oxidative reactions that involve iron uptake. Our studies have focused on the regulatory role of rpoS, known to be a sigma factor (sigma 38) that combines with RNA polymerase and is a regulator of those gene products needed to protect cells during dormancy. Since insect cells, during both active growth and dormancy, endure severe environments, analogous protective gene products may be induced. Examples are presented of insect anti-oxidant metabolism, including those involved in the aging process. In addition, we searched several DNA and protein sequence data banks to compare resemblances between anti-oxidant gene products of bacteria and insects.
 ...
PMID:Genetic mechanisms involved in cellular recovery from oxidative stress. 760 42

Mycobacteria are intracellular pathogens that survive and grow in host macrophages. Following phagocytosis, sustained intracellular bacterial growth depends on its ability to avoid destruction by macrophage-mediated host defences such as lysosomal enzymes, reactive oxygen and the reactive nitrogen intermediates. This suggests that the interaction between host cell and microbe is delicately balanced, and can be tipped in favour of either organism. The identification of Mycobacterium tuberculosis H37Rv (MTB) genes expressed within host cells would contribute greatly to the development of new strategies to fight tuberculosis. In the present study, we compared MTB gene expression in the course of intra- (human macrophages) and extracellular growth (Sauton's medium) to ascertain whether differences might occur between gene-expression patterns in the two habitats of replication. Using reverse-transcriptase polymerase chain reaction (RT-PCR) on a group of 14 MTB-Complex-specific genes, we found that MT10Sa (a small stable RNA), 35 kDa (unknown), ahpC (alkyl hydroperoxide reductase, AhpC), sigF (alternative RNA Polymerase sigma factor), and katG (catalase-peroxidase, HPI) genes are expressed in both the environments, while Ag85B, Ag85C (members of the Antigen 85 Complex), rpoV (RNA Polymerase sigma factor) and ESAT6 (early secretory antigen, 6 kDa) are expressed only in the in vitro culture; on the other hand, Ag85A (Antigen 85 Complex), rpoB (RNA Polymerase beta sub-unit), pab (Protein antigen b), invA and invB genes (encoding proteins that show homologies with p60 of Listeria monocytogenes) are expressed only inside the macrophage. Positive RT-PCR products on cDNAs for these genomic regions were not obtained from approximately 1000-fold more bacteria grown in Laboratory Broth. Identification of M. tuberculosis genes expressed in response to phagocytosis by human macrophages increases our basic understanding of the host-pathogen interaction, and helps to identify bacterial factors necessary for in vivo survival and growth.
 ...
PMID:Mycobacterium tuberculosis H37Rv comparative gene-expression analysis in synthetic medium and human macrophage. 1094 May 66