Identification of a hemerythrin-like domain in a P1B-type transport ATPase.
The P(1B)-type ATPases couple the energy of ATP hydrolysis to metal ion translocation across cell membranes. Important for prokaryotic metal resistance and essential metal distribution in eukaryotes, P(1B)-ATPases are divided into subclasses on the basis of their metal substrate specificities. Sequence analysis of putative P(1B-5)-ATPases, for which the substrate has not been identified, led to the discovery of a C-terminal soluble domain homologous to hemerythrin (Hr) proteins and domains. The Hr domain from the Acidothermus cellulolyticus P(1B-5)-ATPase was cloned, expressed, and purified (P(1B-5)-Hr). P(1B-5)-Hr binds two iron ions per monomer and adopts a predominantly helical fold. Optical absorption features of the iron-loaded and azide-treated protein are consistent with features observed for other Hr proteins. Autoxidation to the met form is very rapid, as reported for other prokaryotic Hr domains. The presence of a diiron center was confirmed by electron paramagnetic resonance (EPR) and X-ray absorption spectroscopic (XAS) data. The occurrence of a Hr-like domain in a P-type ATPase is unprecedented and suggests new regulatory mechanisms as well as an expanded function for Hr proteins in biology.
Traverso
Matthew E
ME
Department of Biochemistry, Northwestern University, Evanston, Illinois 60208, USA.
Subramanian
Poorna
P
Davydov
Roman
R
Hoffman
Brian M
BM
Stemmler
Timothy L
TL
Rosenzweig
Amy C
AC
D000192:Actinomycetales / Q000201:enzymology*; D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D000595:Amino Acid Sequence; D002942:Circular Dichroism; D003001:Cloning, Molecular; D004578:Electron Spin Resonance Spectroscopy; D006422:Hemerythrin / Q000737:chemistry*; D008969:Molecular Sequence Data; D055550:Protein Stability; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D013696:Temperature; D056928:X-Ray Absorption Spectroscopy
D006422:Hemerythrin; D000251:Adenosine Triphosphatases