Globin domain interactions control heme pocket conformation and oligomerization of globin coupled sensors.
Globin coupled sensors (GCS) are O2-sensing proteins used by bacteria to monitor the surrounding gaseous environment. To investigate the biphasic O2dissociation kinetics observed for full-length GCS proteins, isolated globin domains from Pectobacterium carotovorum ssp. carotovorum (PccGlobin), and Bordetella pertussis (BpeGlobin), have been characterized. PccGlobin is found to be dimeric, while BpeGlobin is monomeric, indicating key differences in the globin domain dimer interface. Through characterization of wild type globin domains and globin variants with mutations at the dimer interface and within the distal pocket, dimerization of the globin domain is demonstrated to correlate with biphasic dissociation kinetics. Furthermore, a distal pocket tyrosine is identified as the primary hydrogen bond donor, while a secondary hydrogen bond donor within the distal heme pocket is involved in conformation(s) that lead to the second O2dissociation rate. These findings highlight the role of the globin dimer interface in controlling properties of both the heme pocket and full-length GCS proteins.
Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, GA 30322 USA.
Shannon
S
Rivera
Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, GA 30322 USA.
Justin L
JL
Burns
Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, GA 30322 USA.
Gregory E
GE
Vansuch
Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, GA 30322 USA.
Bryant
B
Chica
Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, GA 30322 USA. Electronic address: emily.weinert@emory.edu.
Emily E
EE
Weinert
D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D001665:Binding Sites; D005914:Globins / Q000737:chemistry* / Q000235:genetics; D006418:Heme / Q000737:chemistry* / Q000235:genetics; D016973:Pectobacterium carotovorum / Q000737:chemistry* / Q000235:genetics; D000072417:Protein Domains
D001426:Bacterial Proteins; D006418:Heme; D005914:Globins
Globin coupled sensor; Globin domain; Oligomerization state; Oxygen sensor