Hydrogen sulfide stimulates the catalytic activity of a heme-regulated phosphodiesterase from Escherichia coli (Ec DOS)

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• 作者：Hiroto Takahashi¹ ; Madoka Sekimoto¹ ; Masahiro Tanaka ; Atsunari Tanaka² ; Jotaro Igarashi³ ; Toru Shimizu ; ^{shimizu@tagen.tohoku.ac.jp}
• 关键词：PDE ; phosphodiesterase ; Ec DOS ; EscherichiacoliDirect Oxygen Sensor or heme-regulated phosphodiesterase from Escherichia coli ; c-di-GMP ; bis-(3&prime ; -5&prime ; )-cyclic dimeric guanosine monophosphate ; l-di-GMP ; linear di-GMP ; or pGpG ; Fe(III) ; Fe(III)&nda
• 刊名：Journal of Inorganic Biochemistry
• 出版年：2012
• 期刊代码：53_01620134
• 类别：ch
• 出版时间：April, 2012
• 卷：109
• 期：Complete
• 页码：66-71
• 文件大小：699 K

摘要

Ec DOS, a heme-regulated phosphodiesterase from Escherichia coli, is an oxygen sensor enzyme composed of a heme-bound O₂ sensor domain at the N-terminus and a catalytic domain at the C-terminus. The catalytic activity of Ec DOS is substantially enhanced with the formation of a Fe(II) heme-O₂ complex. The physiological importance of H₂S as a fourth signaling gas molecule in addition to O₂, CO and NO is an emerging focus of research, since H₂S participates in various physiological functions. In the present study, we showed that catalysis by Ec DOS is markedly increased by H₂S under aerobic conditions. Absorption spectral findings suggest that SH^{鈭?/sup>-modified heme iron complexes, such as Fe(III)-SH鈭?/sup> and Fe(II)-O₂ complexes, represent the active species for H₂S-induced catalysis. We further examined the role of Cys residues in H₂S-induced catalysis using Cys 鈫?#xA0;Ala mutant enzymes. Based on the collective data, we speculate that H₂S-induced catalytic enhancement is facilitated by an admixture of Fe(III)-SH鈭?/sup> and Fe(II)-O₂ complexes formed during catalysis and modification of specific Cys residue(s) in the catalytic domain.}