Leu65 in the heme distal side is critical for the stability of the Fe(II)-O 2 complex of YddV, a globin-coupled oxygen sensor diguanylate cyclase

Kyosuke Nakajima, Kenichi Kitanishi, Kazuo Kobayashi, Nagao Kobayashi, Jotaro Igarashi, Toru Shimizu

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)

Abstract

YddV is a globin-coupled oxygen sensor enzyme in that O 2 binding to the Fe(II) heme in the sensor domain substantially enhances its diguanylate cyclase activity. The Fe(III) heme-bound enzyme is also the active form. Amino acid sequence comparisons indicate that Leu65 is well conserved in globin-coupled oxygen sensor enzymes. Absorption spectra of the Fe(III) heme complexes of L65G, L65M, L65Q and L65T mutants of the isolated heme domain of YddV (YddV-heme) were substantially different from that of the wild-type protein. Specifically, Soret bands of the 6-coordinated high-spin Fe(III) complexes of mutant proteins (with H 2O and His98 as axial ligands) were located at around 403-406 nm, distinct from that (391 nm) of the 5-coordinated high-spin Fe(III) complex of wild-type protein with His98 as the axial ligand. The autooxidation rate constant (> 0.10 min - 1) of the Fe(II)-O 2 complex of L65G was substantially higher than that (0.011 min - 1) of the wild-type protein. Affinities of O 2 for the Fe(II) complexes of L65G and L65T were markedly higher than that for the wild-type protein. Thus, we suggest that the well-conserved Leu65 located in the heme distal side is critical for restricting water access to the heme distal side to avoid rapid autooxidation of YddV, which needs a stable Fe(II)-O 2 complex with a low autooxidation rate.

Original languageEnglish
Pages (from-to)163-170
Number of pages8
JournalJournal of Inorganic Biochemistry
Volume108
DOIs
Publication statusPublished - 2012 Mar

Keywords

  • Diguanylate cyclase
  • Heme
  • Oxygen sensor
  • c-di-GMP

ASJC Scopus subject areas

  • Biochemistry
  • Inorganic Chemistry

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