Article

Journal of Structural and Functional Genomics

, Volume 13, Issue 1, pp 27-36

Crystal structure of a putative isochorismatase hydrolase from Oleispira antarctica

  • Anna M. GoralAffiliated withDepartment of Molecular Physiology and Biological Physics, University of VirginiaMidwest Center for Structural GenomicsInter-Faculty Interdisciplinary Doctoral Studies in Natural Sciences and Mathematics, University of WarsawFaculty of Chemistry, University of Warsaw
  • , Karolina L. TkaczukAffiliated withDepartment of Molecular Physiology and Biological Physics, University of VirginiaMidwest Center for Structural Genomics
  • , Maksymilian ChruszczAffiliated withDepartment of Molecular Physiology and Biological Physics, University of VirginiaMidwest Center for Structural Genomics
  • , Olga KaganAffiliated withBanting and Best Department of Medical Research, University of TorontoMidwest Center for Structural Genomics
  • , Alexei SavchenkoAffiliated withBanting and Best Department of Medical Research, University of TorontoMidwest Center for Structural Genomics
  • , Wladek MinorAffiliated withDepartment of Molecular Physiology and Biological Physics, University of VirginiaMidwest Center for Structural Genomics Email author 

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Abstract

Isochorismatase-like hydrolases (IHL) constitute a large family of enzymes divided into five structural families (by SCOP). IHLs are crucial for siderophore-mediated ferric iron acquisition by cells. Knowledge of the structural characteristics of these molecules will enhance the understanding of the molecular basis of iron transport, and perhaps resolve which of the mechanisms previously proposed in the literature is the correct one. We determined the crystal structure of the apo-form of a putative isochorismatase hydrolase OaIHL (PDB code: 3LQY) from the antarctic γ-proteobacterium Oleispira antarctica, and did comparative sequential and structural analysis of its closest homologs. The characteristic features of all analyzed structures were identified and discussed. We also docked isochorismate to the determined crystal structure by in silico methods, to highlight the interactions of the active center with the substrate. The putative isochorismate hydrolase OaIHL from O. antarctica possesses the typical catalytic triad for IHL proteins. Its active center resembles those IHLs with a D–K–C catalytic triad, rather than those variants with a D–K–X triad. OaIHL shares some structural and sequential features with other members of the IHL superfamily. In silico docking results showed that despite small differences in active site composition, isochorismate binds to in the structure of OaIHL in a similar mode to its binding in phenazine biosynthesis protein PhzD (PDB code 1NF8).

Keywords

Iron uptake Isochorismatase hydrolases Structural comparison of isochorismatases Structural genomics