Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.13.3 (histidine kinase)
 2,405 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The archetypal two-component signal transduction systems include a sensor histidine kinase and a response regulator, which consists of a receiver CheY-like domain and a DNA-binding domain. Sequence analysis of the sensor kinases and response regulators encoded in complete bacterial and archaeal genomes revealed complex domain architectures for many of them and allowed the identification of several novel conserved domains, such as PAS, GAF, HAMP, GGDEF, EAL, and HD-GYP. All of these domains are widely represented in bacteria, including 19 copies of the GGDEF domain and 17 copies of the EAL domain encoded in the Escherichia coli genome. In contrast, these novel signaling domains are much less abundant in bacterial parasites and in archaea, with none at all found in some archaeal species. This skewed phyletic distribution suggests that the newly discovered complexity of signal transduction systems emerged early in the evolution of bacteria, with subsequent massive loss in parasites and some horizontal dissemination among archaea. Only a few proteins containing these domains have been studied experimentally, and their exact biochemical functions remain obscure; they may include transformations of novel signal molecules, such as the recently identified cyclic diguanylate. Recent experimental data provide the first direct evidence of the participation of these domains in signal transduction pathways, including regulation of virulence genes and extracellular enzyme production in the human pathogens Bordetella pertussis and Borrelia burgdorferi and the plant pathogen Xanthomonas campestris. Gene-neighborhood analysis of these new domains suggests their participation in a variety of processes, from mercury and phage resistance to maintenance of virulence plasmids. It appears that the real picture of the complexity of phosphorelay signal transduction in prokaryotes is only beginning to unfold.
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PMID:Novel domains of the prokaryotic two-component signal transduction systems. 1155 34

The filamentous fungus Trichoderma harzianum, strain IMI 393899, was able to grow in the presence of the heavy metals cadmium and mercury. The main objective of this research was to study the molecular mechanisms underlying the tolerance of the fungus T. harzianum to cadmium. The suppression subtractive hybridization (SSH) method was used for the characterization of the genes of T. harzianum implicated in cadmium tolerance compared with those expressed in the response to the stress induced by mercury. Finally, the effects of cadmium exposure were also validated by measuring the expression levels of the putative genes coding for a glucose transporter, a plasma membrane ATPase, a Cd(2+)/Zn(2+) transporter protein and a two-component system sensor histidine kinase YcbA, by real-time-PCR. By using the aforementioned SSH strategy, it was possible to identify 108 differentially expressed genes of the strain IMI 393899 of T. harzianum grown in a mineral substrate with the addition of cadmium. The expressed sequence tags identified by SSH technique were encoding different genes that may be involved in different biological processes, including those associated to primary and secondary metabolism, intracellular transport, transcription factors, cell defence, signal transduction, DNA metabolism, cell growth and protein synthesis. Finally, the results show that in the mechanism of tolerance to cadmium a possible signal transduction pathway could activate a Cd(2+)/Zn(2+) transporter protein and/or a plasma membrane ATPase that could be involved in the compartmentalization of cadmium inside the cell.
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PMID:Cadmium induces cadmium-tolerant gene expression in the filamentous fungus Trichoderma harzianum. 2634 55