Cytochrome 572 is a conspicuous membrane protein with iron oxidation activity purified directly from a natural acidophilic microbial community

Journal Article · Tue Jan 01 00:00:00 EST 2008 · The ISME Journal: Multidisciplinary Journal of Microbial Ecology

OSTI ID:958815

Verberkmoes, Nathan C ^[1]; Singer, Steven ^[2]; Shah, Manesh B ^[1]; Thelen, Michael P. ^[3]; Banfield, Jillian F. ^[3]

---

1. ORNL
2. Lawrence Livermore National Laboratory (LLNL)
3. University of California, Berkeley

We have discovered and characterized a novel membrane cytochrome of an iron oxidizing microbial biofilm obtained from the surface of extremely acidic mine water. This protein was initially identified through proteogenomic analysis as one of many novel gene products of Leptospirillum group II, the dominant bacterium of this community (Ram et al, 2005, Science 308, 1915-20). Extraction of proteins directly from environmental biofilm samples followed by membrane fractionation, detergent solubilization and gel filtration chromatography resulted in the purification of an abundant yellow-red protein. Covalently bound to heme, the purified cytochrome has a unique spectral signature at 572 nm and is thus called Cyt572. It readily oxidizes Fe2+ even in the presence of Fe3+ over a pH range from 0.95 to 3.4. Independent experiments involving 2D blue-native polyacrylamide gel electrophoresis and chemical crosslinking establish a homotetrameric structure for Cyt572. Also, circular dichroism spectroscopy indicates that the protein is largely beta-stranded, consistent with an outer membrane location. Although no significant sequence homology to the full-length cytochrome is detected in protein databases, environmental DNA sequences from both Leptospirillum groups II and III reveal at least 17 strain variants of Cyt572. Due to its abundance, cellular location and Fe2+ oxidation activity, we propose Cyt572 is the iron oxidase of the Leptospirillum bacteria, providing a critical function for fitness within the ecological niche of this acidophilic microbial community.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 958815
• Journal Information: The ISME Journal: Multidisciplinary Journal of Microbial Ecology, Vol. 2, Issue 5; ISSN 0027-8424
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
BACTERIA
CHROMATOGRAPHY
CYTOCHROMES
DETERGENTS
DICHROISM
DNA
ELECTROPHORESIS
FILTRATION
FRACTIONATION
GENES
HEME
IRON
MEMBRANE PROTEINS
MEMBRANES
OXIDASES
OXIDATION
PROTEINS
PURIFICATION
SPECTROSCOPY
STRAINS
acid mine drainage
Cyt572
Cytochrome 572
n-dodecyl-&beta
-D-maltoside
Leptospirillum group II
mass spectrometry
polyacrylamide gel electrophoresis