Novel zinc-binding center and a temperature switch in the Bacillus stearothermophilus L1 lipase.
The bacterial thermoalkalophilic lipases optimally hydrolyze saturated fatty acids at elevated temperatures. They also have significant sequence homology with staphylococcal lipases, and both the thermoalkalophilic and staphylococcal lipases are grouped as the lipase family I.5. We report here the first crystal structure of the lipase family I.5, the structure of a thermoalkalophilic lipase from Bacillus stearothermophilus L1 (L1 lipase) determined at 2.0-A resolution. The structure is in a closed conformation, and the active site is buried under a long lid helix. Unexpectedly, the structure exhibits a zinc-binding site in an extra domain that accounts for the larger molecular size of the family I.5 enzymes in comparison to other microbial lipases. The zinc-coordinated extra domain makes tight interactions with the loop extended from the C terminus of the lid helix, suggesting that the activation of the family I.5 lipases may be regulated by the strength of the interactions. The unusually long lid helix makes strong hydrophobic interactions with its neighbors. The structural information together with previous biochemical observations indicate that the temperature-mediated lid opening is triggered by the thermal dissociation of the hydrophobic interactions.
Jeong
Seong-Tae
ST
Center for Cellular Switch Protein Structure and Environmental Bioresources Lab, Korea Research Institute of Bioscience and Biotechnology, 52 Euh-eun-dong, Yusong-gu, Daejon, Korea.
Kim
Hyung-Kwoun
HK
Kim
Seung-Jun
SJ
Chi
Seung-Wook
SW
Pan
Jae-Gu
JG
Oh
Tae-Kwang
TK
Ryu
Seong-Eon
SE
D000595:Amino Acid Sequence; D001665:Binding Sites; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D029968:Escherichia coli Proteins; D001411:Geobacillus stearothermophilus / Q000201:enzymology*; D008245:Lysophospholipase / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D033903:Periplasmic Proteins; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013696:Temperature; D015032:Zinc / Q000737:chemistry / Q000378:metabolism*
D029968:Escherichia coli Proteins; D033903:Periplasmic Proteins; D008245:Lysophospholipase; C400724:tesA protein, E coli; D015032:Zinc