PubMed:10482791 JSONTXT

{"project":"Anatomy-MAT","denotations":[{"id":"T1","span":{"begin":158,"end":172},"obj":"Body_part"}],"attributes":[{"id":"A1","pred":"mat_id","subj":"T1","obj":"http://purl.obolibrary.org/obo/MAT_0000192"}],"text":"Identification of amino acids responsible for the oxygen sensitivity of ferredoxins from Anabaena variabilis using site-directed mutagenesis.\nThe filamentous cyanobacterium Anabaena variabilis (ATCC 29413) possesses two molybdenum dependent nitrogenase systems, nif1 and nif2. The nif1 system is regulated by a developmental program involving heterocyst differentiation; the nif2 system is expressed in all cells only under anaerobic conditions and the expression is controlled environmentally. The genes fdxH1 and fdxH2, encoding two [2Fe-2S] ferredoxins, are part of the these two distinct and differently regulated nif gene clusters. The sensitivity of both ferredoxins to oxygen was different; the half-life of FdxH2 in air was only approximately 1.5 h, while FdxH1 retained 80% of its nitrogenase activity after 24 h. We used site-directed mutagenesis to identify the role of individual amino acid residues responsible for oxygen sensitivity and found out that the FdxH2 double mutant I76A/V77L was much more resistant to oxygen than the wild-type ferredoxin (FdxH2) and similar to FdxH1. By modelling it was shown that the accessibility of the cavity around the iron-sulfur cluster was responsible for that."}

{"project":"CyanoBase","denotations":[{"id":"T1","span":{"begin":505,"end":510},"obj":"protein"},{"id":"T2","span":{"begin":515,"end":520},"obj":"protein"},{"id":"T3","span":{"begin":715,"end":720},"obj":"protein"},{"id":"T4","span":{"begin":764,"end":769},"obj":"protein"},{"id":"T5","span":{"begin":970,"end":975},"obj":"protein"},{"id":"T6","span":{"begin":1065,"end":1070},"obj":"protein"},{"id":"T7","span":{"begin":1087,"end":1092},"obj":"protein"}],"text":"Identification of amino acids responsible for the oxygen sensitivity of ferredoxins from Anabaena variabilis using site-directed mutagenesis.\nThe filamentous cyanobacterium Anabaena variabilis (ATCC 29413) possesses two molybdenum dependent nitrogenase systems, nif1 and nif2. The nif1 system is regulated by a developmental program involving heterocyst differentiation; the nif2 system is expressed in all cells only under anaerobic conditions and the expression is controlled environmentally. The genes fdxH1 and fdxH2, encoding two [2Fe-2S] ferredoxins, are part of the these two distinct and differently regulated nif gene clusters. The sensitivity of both ferredoxins to oxygen was different; the half-life of FdxH2 in air was only approximately 1.5 h, while FdxH1 retained 80% of its nitrogenase activity after 24 h. We used site-directed mutagenesis to identify the role of individual amino acid residues responsible for oxygen sensitivity and found out that the FdxH2 double mutant I76A/V77L was much more resistant to oxygen than the wild-type ferredoxin (FdxH2) and similar to FdxH1. By modelling it was shown that the accessibility of the cavity around the iron-sulfur cluster was responsible for that."}

{"project":"NCBITAXON","denotations":[{"id":"T1","span":{"begin":89,"end":108},"obj":"OrganismTaxon"},{"id":"T2","span":{"begin":158,"end":172},"obj":"OrganismTaxon"},{"id":"T3","span":{"begin":173,"end":192},"obj":"OrganismTaxon"}],"attributes":[{"id":"A1","pred":"db_id","subj":"T1","obj":"264691"},{"id":"A2","pred":"db_id","subj":"T2","obj":"102234"},{"id":"A3","pred":"db_id","subj":"T3","obj":"264691"}],"text":"Identification of amino acids responsible for the oxygen sensitivity of ferredoxins from Anabaena variabilis using site-directed mutagenesis.\nThe filamentous cyanobacterium Anabaena variabilis (ATCC 29413) possesses two molybdenum dependent nitrogenase systems, nif1 and nif2. The nif1 system is regulated by a developmental program involving heterocyst differentiation; the nif2 system is expressed in all cells only under anaerobic conditions and the expression is controlled environmentally. The genes fdxH1 and fdxH2, encoding two [2Fe-2S] ferredoxins, are part of the these two distinct and differently regulated nif gene clusters. The sensitivity of both ferredoxins to oxygen was different; the half-life of FdxH2 in air was only approximately 1.5 h, while FdxH1 retained 80% of its nitrogenase activity after 24 h. We used site-directed mutagenesis to identify the role of individual amino acid residues responsible for oxygen sensitivity and found out that the FdxH2 double mutant I76A/V77L was much more resistant to oxygen than the wild-type ferredoxin (FdxH2) and similar to FdxH1. By modelling it was shown that the accessibility of the cavity around the iron-sulfur cluster was responsible for that."}

{"project":"Anatomy-UBERON","denotations":[{"id":"T1","span":{"begin":1150,"end":1156},"obj":"Body_part"}],"attributes":[{"id":"A1","pred":"uberon_id","subj":"T1","obj":"http://purl.obolibrary.org/obo/UBERON_0002553"}],"text":"Identification of amino acids responsible for the oxygen sensitivity of ferredoxins from Anabaena variabilis using site-directed mutagenesis.\nThe filamentous cyanobacterium Anabaena variabilis (ATCC 29413) possesses two molybdenum dependent nitrogenase systems, nif1 and nif2. The nif1 system is regulated by a developmental program involving heterocyst differentiation; the nif2 system is expressed in all cells only under anaerobic conditions and the expression is controlled environmentally. The genes fdxH1 and fdxH2, encoding two [2Fe-2S] ferredoxins, are part of the these two distinct and differently regulated nif gene clusters. The sensitivity of both ferredoxins to oxygen was different; the half-life of FdxH2 in air was only approximately 1.5 h, while FdxH1 retained 80% of its nitrogenase activity after 24 h. We used site-directed mutagenesis to identify the role of individual amino acid residues responsible for oxygen sensitivity and found out that the FdxH2 double mutant I76A/V77L was much more resistant to oxygen than the wild-type ferredoxin (FdxH2) and similar to FdxH1. By modelling it was shown that the accessibility of the cavity around the iron-sulfur cluster was responsible for that."}

{"project":"CL-cell","denotations":[{"id":"T1","span":{"begin":343,"end":353},"obj":"Cell"}],"attributes":[{"id":"A1","pred":"cl_id","subj":"T1","obj":"http://purl.obolibrary.org/obo/CL:0000724"}],"text":"Identification of amino acids responsible for the oxygen sensitivity of ferredoxins from Anabaena variabilis using site-directed mutagenesis.\nThe filamentous cyanobacterium Anabaena variabilis (ATCC 29413) possesses two molybdenum dependent nitrogenase systems, nif1 and nif2. The nif1 system is regulated by a developmental program involving heterocyst differentiation; the nif2 system is expressed in all cells only under anaerobic conditions and the expression is controlled environmentally. The genes fdxH1 and fdxH2, encoding two [2Fe-2S] ferredoxins, are part of the these two distinct and differently regulated nif gene clusters. The sensitivity of both ferredoxins to oxygen was different; the half-life of FdxH2 in air was only approximately 1.5 h, while FdxH1 retained 80% of its nitrogenase activity after 24 h. We used site-directed mutagenesis to identify the role of individual amino acid residues responsible for oxygen sensitivity and found out that the FdxH2 double mutant I76A/V77L was much more resistant to oxygen than the wild-type ferredoxin (FdxH2) and similar to FdxH1. By modelling it was shown that the accessibility of the cavity around the iron-sulfur cluster was responsible for that."}