共查询到20条相似文献,搜索用时 31 毫秒
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Butachlor, a commonly used herbicide adversely affects the nitrogen fixing capability of Anabaena, an acclaimed nitrogen fixer in
the Indian paddy fields. The nitrogen fixation in Anabaena is triggered by the excision of nifD element by xisA gene leading to
rearrangement of nifD forming nifHDK operon in the heterocyst of Anabaena sp. PCC7120. Functional elucidation adjudged
through in-silico analysis revealed that xisA belongs to integrase family of tyrosine recombinase. The predicted functional partners
with XisA protein that have shown cooccurence with this protein in a network are mainly hypothetical proteins with unknown
functions except psaK1 whose exact function in photosystem I is not yet known. The focus of this study was to find out the relation
between XisA and butachlor using in-silico approaches. The XisA protein was modeled and its active sites were identified. Docking
studies revealed that butachlor binds at the active site of XisA protein hampering its excision ability vis-à-vis nif genes in Anabaena
sp. PCC7120. This study reveals that butachlor is not directly involved in hampering the nitrogen fixing ability of Anabaena sp.
PCC7120 but by arresting the excision ability of XisA protein necessary for the functioning of nif gene and nitrogen fixation. 相似文献
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Jing-jing Lu Lei Shi Wen-li Chen Li Wang 《World journal of microbiology & biotechnology》2014,30(10):2673-2680
In response to deprivation of combined nitrogen, the filamentous cyanobacterium Anabaena sp. strain PCC 7120 develops heterocyst, which is specifically involved in the nitrogen fixation. In this study, we focused on the regulation of HanA, a histone-like protein, in heterocyst development. Electrophoretic mobility shift assay results showed that NtcA, a global nitrogen regulator necessary for heterocyst differentiation, could bind to two NtcA-binding motifs in the hanA promoter region. qPCR results also showed that NtcA may regulate the expression of hanA. By using the hanA promoter-controlled gfp as a reporter gene and performing western blot we found that the amount of HanA in mature heterocysts was decreased gradually. 相似文献
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《Anaerobe》2001,7(3):159-169
The kdp operon of Clostridium acetobutylicum codes for the high affinity K+-translocating Kdp system (P-type ATPase). Beside the three large proteins KdpA, KdpB and KdpC, the kdp operon encodes the two small peptides KdpZ, KdpY and the KdpX protein. The truncation of the clostridial kdpZ and/or the kdpY gene has a significant impact on the growth of an E. coli mutant (TK2205), which is unable to grow at low potassium concentrations. These two genes together with kdpX are essential to maintain the wild-type K+-pump capacity of the clostridial Kdp system. Also the ATPase activity itself, the substrate specifity, and the cation specifity are determined in a major way by KdpZ, KdpY, and KdpX. Thus, this report shows the importance of the KdpZ, KdpY, and KdpX proteins for the Kdp-ATPase and therefore the corresponding operon should now be referred to as kdpZYABCX. 相似文献
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Laura Bertini Valeria Cafaro Silvia Proietti Carlo Caporale Paola Capasso Carla Caruso Alberto Di Donato 《Biochimie》2013
Pseudomonas sp. OX1 is able to metabolize toluene and o-xylene through the TOU catabolic pathway, whereas its mutant M1 strain was found to be able to use m- and p-xylene as carbon and energy source, using the TOL catabolic pathway. Here we report the complete nucleotide sequence of the phe lower operon of the TOU catabolic pathway, and the sequence of the last four genes of the xyl-like lower operon of the TOL catabolic pathway. DNA sequence analysis shows the gene order within the operons to be pheCDEFGHI (phe operon) and xyl-likeQKIH (xyl-like operon), identical to the order found for the isofunctional genes of meta operons in the toluene/xylene pathway of TOL plasmid pWW0 from Pseudomonas putida mt-2 and the phenol/methylphenol pathway of pVIl50 from Pseudomonas sp. CF600. The nucleotide and the deduced amino acid sequences are homologous to the equivalent gene and enzyme sequences from other Pseudomonas meta pathways. Recombinant 2-hydroxymuconic semialdehyde dehydrogenase (HMSD) and 2-hydroxymuconic semialdehyde hydrolase (HMSH), coded by pheCD genes, respectively, and ADA and HOA enzymes from both phe and xyl operons were expressed in E. coli and steady-state kinetic analysis was carried out. The analysis of the kinetic parameters of HMSD and HMSH showed that the enzymes from Pseudomonas sp. OX1 are more specialized to channel metabolites into the two branches of the lower pathway than homologous enzymes from other pseudomonads. The kinetics parameters of recombinant ADA from phe and xyl-like operon were found to be similar to those of homologous enzymes from other Pseudomonas strains. In addition, the enzyme from xyl-like operon showed a substrate affinity three times higher than the enzyme from phe operon. 相似文献
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Katrin G?rtner Sigal Lechno-Yossef Adam J. Cornish C. Peter Wolk Eric L. Hegg 《Applied and environmental microbiology》2012,78(24):8579-8586
H2 generated from renewable resources holds promise as an environmentally innocuous fuel that releases only energy and water when consumed. In biotechnology, photoautotrophic oxygenic diazotrophs could produce H2 from water and sunlight using the cells'' endogenous nitrogenases. However, nitrogenases have low turnover numbers and require large amounts of ATP. [FeFe]-hydrogenases found in other organisms can have 1,000-fold higher turnover numbers and no specific requirement for ATP but are very O2 sensitive. Certain filamentous cyanobacteria protect nitrogenase from O2 by sequestering the enzyme within internally micro-oxic, differentiated cells called heterocysts. We heterologously expressed the [FeFe]-hydrogenase operon from Shewanella oneidensis MR-1 in Anabaena sp. strain PCC 7120 using the heterocyst-specific promoter PhetN. Active [FeFe]-hydrogenase was detected in and could be purified from aerobically grown Anabaena sp. strain PCC 7120, but only when the organism was grown under nitrate-depleted conditions that elicited heterocyst formation. These results suggest that the heterocysts protected the [FeFe]-hydrogenase against inactivation by O2. 相似文献
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Nitrogen-fixing cultures of two species of the filamentous, heterocystous cyanobacterium Anabaena, namely Anabaena sp. strain L-31 and Anabaena torulosa were found to be highly tolerant to 60Co gamma radiation. No adverse effect on diazotrophic growth and metabolism were observed up to a dose of 5 kGy. At higher
doses, radiation tolerance showed a correspondence with the inherent osmotolerance, with Anabaena L-31 being the more radiation tolerant as well as osmotolerant strain. In Anabaena L-31, exposure to 6 kGy of gamma rays resulted in genome disintegration, but did not reduce viability. Irradiation delayed
heterocyst differentiation and nitrogen fixation, and marginally affected diazotrophic growth. All the affected parameters
recovered after a short lag, without any discernible postirradiation phenotype. The radiation tolerance of these Gram-negative
photoautodiazotrophs is comparable with that of the adiazotrophic photoautotrophic cyanobacterium Chroococcidiopsis or adiazotrophic heterotroph Deinococcus radiodurans. This is the first report of extreme radioresistance in nitrogen-fixing Anabaena cultures. 相似文献
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