Roles of glutamates and metal ions in a rationally designed nitric oxide reductase based on myoglobin

Journal Article · Tue May 11 00:00:00 EDT 2010 · Proceedings of the National Academy of Sciences of the United States of America

DOI:https://doi.org/10.1073/pnas.1000526107· OSTI ID:1014299

Lin, Y W; Robinson, H; Yeung, N; Gao, Y -G; Miner, K D; Tian, S; Lu, Y

A structural and functional model of bacterial nitric oxide reductase (NOR) has been designed by introducing two glutamates (Glu) and three histidines (His) in sperm whale myoglobin. X-ray structural data indicate that the three His and one Glu (V68E) residues bind iron, mimicking the putative FeB site in NOR, while the second Glu (I107E) interacts with a water molecule and forms a hydrogen bonding network in the designed protein. Unlike the first Glu (V68E), which lowered the heme reduction potential by {approx}110 mV, the second Glu has little effect on the heme potential, suggesting that the negatively charged Glu has a different role in redox tuning. More importantly, introducing the second Glu resulted in a {approx}100% increase in NOR activity, suggesting the importance of a hydrogen bonding network in facilitating proton delivery during NOR reactivity. In addition, EPR and X-ray structural studies indicate that the designed protein binds iron, copper, or zinc in the FeB site, each with different effects on the structures and NOR activities, suggesting that both redox activity and an intermediate five-coordinate heme-NO species are important for high NOR activity. The designed protein offers an excellent model for NOR and demonstrates the power of using designed proteins as a simpler and more well-defined system to address important chemical and biological issues.

• Research Organization: Brookhaven National Lab. (BNL), Upton, NY (United States)
• Sponsoring Organization: DOE - OFFICE OF SCIENCE
• DOE Contract Number: DE-AC02-98CH10886
• OSTI ID: 1014299
• Report Number(s): BNL-93655-2010-JA; PNASA6; R&D Project: BO-070; KP1605010; TRN: US201111%%252
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America, Vol. 107, Issue 19; 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
BONDING
CETACEANS
COPPER
FUNCTIONAL MODELS
HEME
HYDROGEN
IRON
MYOGLOBIN
NITRIC OXIDE
OXIDOREDUCTASES
PROTEINS
PROTONS
RESIDUES
WATER
ZINC
biomimetric models
heme-copper oxidase
metalloprotein
protein design
protein engineering