Nam KH

References (6)

Title : Structural and functional analyses of the lipase CinB from Enterobacter asburiae - Shang_2019_Biochem.Biophys.Res.Commun_519_274
Author(s) : Shang F , Lan J , Liu W , Chen Y , Wang L , Zhao J , Chen J , Gao P , Ha NC , Quan C , Nam KH , Xu Y
Ref : Biochemical & Biophysical Research Communications , 519 :274 , 2019
Abstract : Lipases are widely present in various plants, animals and microorganisms, constituting a large category of enzymes. They have the ability to catalyze the cleavage of ester bonds. The lipase CinB from Enterobacter asburiae (E. asburiae) is an acetyl esterase. The primary amino acid sequence suggests that the EaCinB protein belongs to the alpha/beta-hydrolase (ABH) superfamily of the esterase/lipase superfamily. However, its molecular functions have not yet been determined. Here, we report the crystal structure of E. asburiae CinB at a 1.45A resolution. EaCinB contains a signal peptide, cap domain and catalytic domain. The active site of EaCinB contains the catalytic triad (Ser180-His307-Asp277) on the catalytic domain. The oxyanion hole is composed of Gly106 and Gly107 within the conserved sequence motif HGGG (amino acid residues 106-109). The substrate is accessible between the alpha1 and alpha2 helices or the alpha1 helix and catalytic domain. Narrow substrate pockets are formed by the alpha2 helix of the cap domain. Site-directed mutagenesis showed that EaCinB-W208H exhibits a higher catalytic ability than EaCinB-WT by approximately nine times. Our results provide insight into the molecular function of EaCinB.
ESTHER : Shang_2019_Biochem.Biophys.Res.Commun_519_274
PubMedSearch : Shang_2019_Biochem.Biophys.Res.Commun_519_274
PubMedID: 31493870
Gene_locus related to this paper: entas-cinB

Title : Structural insight into the carboxylesterase BioH from Klebsiella pneumoniae - Wang_2019_Biochem.Biophys.Res.Commun_520_538
Author(s) : Wang L , Chen Y , Shang F , Liu W , Lan J , Gao P , Ha NC , Nam KH , Dong Y , Quan C , Xu Y
Ref : Biochemical & Biophysical Research Communications , 520 :538 , 2019
Abstract : The BioH carboxylesterase which is a typical alpha/beta-hydrolase enzyme involved in biotin synthetic pathway in most bacteria. BioH acts as a gatekeeper and blocks the further elongation of its substrate. In the pathogen Klebsiella pneumoniae, BioH plays a critical role in the biosynthesis of biotin. To better understand the molecular function of BioH, we determined the crystal structure of BioH from K. pneumoniae at 2.26A resolution using X-ray crystallography. The structure of KpBioH consists of an alpha-beta-alpha sandwich domain and a cap domain. B-factor analysis revealed that the alpha-beta-alpha sandwich domain is a rigid structure, while the loops in the cap domain shows the structural flexibility. The active site of KpBioH contains the catalytic triad (Ser82-Asp207-His235) on the interface of the alpha-beta-alpha sandwich domain, which is surrounded by the cap domain. Size exclusion chromatography shows that KpBioH prefers the monomeric state in solution, whereas two-fold symmetric dimeric formation of KpBioH was observed in the asymmetric unit, the conserved Cys31-based disulfide bonds can maintain the irreversible dimeric formation of KpBioH. Our study provides important structural insight for understanding the molecular mechanisms of KpBioH and its homologous proteins.
ESTHER : Wang_2019_Biochem.Biophys.Res.Commun_520_538
PubMedSearch : Wang_2019_Biochem.Biophys.Res.Commun_520_538
PubMedID: 31615653
Gene_locus related to this paper: klep3-bioh

Title : Biochemical and Structural Analysis of Hormone-sensitive Lipase Homolog EstE7: Insight into the Stabilized Dimerization of HSL-Homolog Proteins - Nam_2010_Bull.Korean.Chem.Soc_31_2627
Author(s) : Nam KH , Park SH , Lee WH , Hwang KY
Ref : Bull Korean Chem Soc , 31 :2627 , 2010
Abstract : Hormone sensitive lipase (HSL) plays a major role in energy homeostasis and lipid metabolism. Several crystal structures of HSL-homolog proteins have been identified, which has led to a better understanding of its molecular function. HSL-homolog proteins exit as both monomer and dimer, but the biochemical and structural basis for such oligomeric states has not been successfully elucidated. Therefore, we determined the crystal structure of HSL-homolog protein EstE7 from a metagenome library at 2.2 resolution and characterized the oligomeric states of EstE7 both structurally and biochemically. EstE7 protein prefers the dimeric state in solution, which is supported by its higher enzymatic activity in the dimeric state. In the crystal form, EstE7 protein shows two-types of dimeric interface. Specifically, dimerization via the external beta8-strand occurred through tight association between two pseudosymmetric folds via salt bridges, hydrogen bonds and van der Waals interactions. This dimer formation was similar to that of other HSL-homolog protein structures such as AFEST, BEFA, and EstE1. We anticipate that our results will provide insight into the oligomeric state of HSL-homolog proteins
ESTHER : Nam_2010_Bull.Korean.Chem.Soc_31_2627
PubMedSearch : Nam_2010_Bull.Korean.Chem.Soc_31_2627
PubMedID:
Gene_locus related to this paper: 9bact-Q0GMU1

Title : Structural and functional analysis of a novel EstE5 belonging to the subfamily of hormone-sensitive lipase - Nam_2009_Biochem.Biophys.Res.Commun_379_553
Author(s) : Nam KH , Kim MY , Kim SJ , Priyadarshi A , Lee WH , Hwang KY
Ref : Biochemical & Biophysical Research Communications , 379 :553 , 2009
Abstract : Hormone-sensitive lipase (HSL) plays an important role in the regulation of rodent fat cell lipolysis. It is regarded as an adipose tissue-specific enzyme whose sole metabolic role is the catalysis of hormone-stimulated lipolysis in mammalian cells. In this report we describe the functional and structural analysis of an EstE5 protein from a soil metagenome library. Function analysis results indicated that EstE5 preferentially hydrolyzes short-chain ester compounds, and our kinetic studies revealed the optimal pH and temperature. Based on the structural analysis, we defined the active site and the binding pocket. Structurally, EstE5 belongs to the HSL family and these structural studies may have applications in the production of value-added products, including pharmaceuticals.
ESTHER : Nam_2009_Biochem.Biophys.Res.Commun_379_553
PubMedSearch : Nam_2009_Biochem.Biophys.Res.Commun_379_553
PubMedID: 19116143
Gene_locus related to this paper: 9bact-Q0GMU2

Title : The crystal structure of an HSL-homolog EstE5 complex with PMSF reveals a unique configuration that inhibits the nucleophile Ser144 in catalytic triads - Nam_2009_Biochem.Biophys.Res.Commun_389_247
Author(s) : Nam KH , Kim SJ , Priyadarshi A , Kim HS , Hwang KY
Ref : Biochemical & Biophysical Research Communications , 389 :247 , 2009
Abstract : The esterase/lipase family (EC 3.1.1.3/EC 3.1.1.1) represents a diverse group of hydrolases that catalyze the cleavage of ester bonds and are widely distributed in animals, plants and microorganisms. Among these enzymes, hormone-sensitive lipases, play a critical role in the regulation of rodent fat cell lipolysis and are regarded as adipose tissue-specific enzymes. Recently, we reported the structural and biological characterization of EstE5 from the metagenome library [K.H. Nam, M.Y. Kim, S.J. Kim, A. Priyadarshi, W.H. Lee, K.Y. Hwang, Structural and functional analysis of a novel EstE5 belonging to the subfamily of hormone-sensitive lipase, Biochem. Biophys. Res. Commun. 379 (2009) 553-556]. The structure of this protein revealed that it belongs to the HSL-family. Here, we report the inhibition of the activity of the HSL-homolog EstE5 protein as determined by the use of esterase/lipase inhibitors. Our results revealed that the EstE5 protein is significantly inhibited by PMSF. In addition, this is the first study to identify the crystal structures of EstE5-PMSF at 2.4 and 2.5A among the HSL-homolog structures. This structural configuration is similar to that adopted when serine proteases are inhibited by PMSF. The results presented here provide valuable information regarding the properties of the HSL-family.
ESTHER : Nam_2009_Biochem.Biophys.Res.Commun_389_247
PubMedSearch : Nam_2009_Biochem.Biophys.Res.Commun_389_247
PubMedID: 19715665
Gene_locus related to this paper: 9bact-Q0GMU2

Title : Structural and functional analysis of a novel hormone-sensitive lipase from a metagenome library -
Author(s) : Nam KH , Kim MY , Kim SJ , Priyadarshi A , Kwon ST , Koo BS , Yoon SH , Hwang KY
Ref : Proteins , 74 :1036 , 2009
PubMedID: 19089974
Gene_locus related to this paper: 9bact-Q0GMU1