Elucidation of haem‐binding sites in the actinobacterial protein HbpS. Issue 2 (21st February 2013)

• Record Type: Journal Article
• Authors: Torda, Andrew E.; Groves, Matthew R.; Wedderhoff, Ina; Ortiz de Orué Lucana, Darío
• Is Part Of: FEMS microbiology letters. Volume 342:Issue 2(2013:May)
• Page Start: 106
• Page End: 112
• Publication Date: 2013-02-21
• Subjects: Microbiology -- Periodicals; 579
• DOI: 10.1111/1574-6968.12093
• Languages: English
• ISSNs: 0378-1097

Abstract

<abstract abstract-type="main" id="fml12093-abs-0001"> <title>Abstract</title> <p>The extracellular haem‐binding protein from <italic>Streptomyces reticuli</italic> (HbpS) has been shown to be involved in redox sensing and to bind haem. However, the residues involved in haem coordination are unknown. Structural alignments to distantly related haem‐binding proteins from <italic>Mycobacterium tuberculosis</italic> were used to identify a candidate haem‐coordinating residue, and site‐directed mutagenesis with UV/Vis spectroscopy was used to assess haem binding <italic>in vivo</italic> and <italic>in vitro</italic>. We present strong evidence that HbpS belongs to the small set of proteins, which do not use histidine to coordinate the metal in the haem group. Further spectroscopic evidence strongly indicates that threonine 113 is actively involved in coordination of haem. Subsequent protein/haem titration experiments show a 1 : 2, protein/haem stoichiometry. We also present data showing the degradation of haem by HbpS <italic>in vivo</italic>. Because HbpS is conserved in many <italic>Actinobacteria</italic>, the presented results are applicable to related species.</p> </abstract>