Crystal structure and substrate specificity of D-galactose-6-phosphate isomerase complexed with substrates.

D-Galactose-6-phosphate isomerase from Lactobacillus rhamnosus (LacAB; EC 5.3.1.26), which is encoded by the tagatose-6-phosphate pathway gene cluster (lacABCD), catalyzes the isomerization of D-galactose-6-phosphate to D-tagatose-6-phosphate during lactose catabolism and is used to produce rare sug...

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Autores principales:	Woo-Suk Jung, Raushan Kumar Singh, Jung-Kul Lee, Cheol-Ho Pan
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2013
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/71cf0dc8719f494a887e65d71da8ebbf
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spelling	oai:doaj.org-article:71cf0dc8719f494a887e65d71da8ebbf2021-11-18T08:57:50ZCrystal structure and substrate specificity of D-galactose-6-phosphate isomerase complexed with substrates.1932-620310.1371/journal.pone.0072902https://doaj.org/article/71cf0dc8719f494a887e65d71da8ebbf2013-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/24015281/pdf/?tool=EBIhttps://doaj.org/toc/1932-6203D-Galactose-6-phosphate isomerase from Lactobacillus rhamnosus (LacAB; EC 5.3.1.26), which is encoded by the tagatose-6-phosphate pathway gene cluster (lacABCD), catalyzes the isomerization of D-galactose-6-phosphate to D-tagatose-6-phosphate during lactose catabolism and is used to produce rare sugars as low-calorie natural sweeteners. The crystal structures of LacAB and its complex with D-tagatose-6-phosphate revealed that LacAB is a homotetramer of LacA and LacB subunits, with a structure similar to that of ribose-5-phosphate isomerase (Rpi). Structurally, LacAB belongs to the RpiB/LacAB superfamily, having a Rossmann-like αβα sandwich fold as has been identified in pentose phosphate isomerase and hexose phosphate isomerase. In contrast to other family members, the LacB subunit also has a unique α7 helix in its C-terminus. One active site is distinctly located at the interface between LacA and LacB, whereas two active sites are present in RpiB. In the structure of the product complex, the phosphate group of D-tagatose-6-phosphate is bound to three arginine residues, including Arg-39, producing a different substrate orientation than that in RpiB, where the substrate binds at Asp-43. Due to the proximity of the Arg-134 residue and backbone Cα of the α6 helix in LacA to the last Asp-172 residue of LacB with a hydrogen bond, a six-carbon sugar-phosphate can bind in the larger pocket of LacAB, compared with RpiB. His-96 in the active site is important for ring opening and substrate orientation, and Cys-65 is essential for the isomerization activity of the enzyme. Two rare sugar substrates, D-psicose and D-ribulose, show optimal binding in the LacAB-substrate complex. These findings were supported by the results of LacA activity assays.Woo-Suk JungRaushan Kumar SinghJung-Kul LeeCheol-Ho PanPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 8, Iss 8, p e72902 (2013)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Woo-Suk Jung Raushan Kumar Singh Jung-Kul Lee Cheol-Ho Pan Crystal structure and substrate specificity of D-galactose-6-phosphate isomerase complexed with substrates.
description	D-Galactose-6-phosphate isomerase from Lactobacillus rhamnosus (LacAB; EC 5.3.1.26), which is encoded by the tagatose-6-phosphate pathway gene cluster (lacABCD), catalyzes the isomerization of D-galactose-6-phosphate to D-tagatose-6-phosphate during lactose catabolism and is used to produce rare sugars as low-calorie natural sweeteners. The crystal structures of LacAB and its complex with D-tagatose-6-phosphate revealed that LacAB is a homotetramer of LacA and LacB subunits, with a structure similar to that of ribose-5-phosphate isomerase (Rpi). Structurally, LacAB belongs to the RpiB/LacAB superfamily, having a Rossmann-like αβα sandwich fold as has been identified in pentose phosphate isomerase and hexose phosphate isomerase. In contrast to other family members, the LacB subunit also has a unique α7 helix in its C-terminus. One active site is distinctly located at the interface between LacA and LacB, whereas two active sites are present in RpiB. In the structure of the product complex, the phosphate group of D-tagatose-6-phosphate is bound to three arginine residues, including Arg-39, producing a different substrate orientation than that in RpiB, where the substrate binds at Asp-43. Due to the proximity of the Arg-134 residue and backbone Cα of the α6 helix in LacA to the last Asp-172 residue of LacB with a hydrogen bond, a six-carbon sugar-phosphate can bind in the larger pocket of LacAB, compared with RpiB. His-96 in the active site is important for ring opening and substrate orientation, and Cys-65 is essential for the isomerization activity of the enzyme. Two rare sugar substrates, D-psicose and D-ribulose, show optimal binding in the LacAB-substrate complex. These findings were supported by the results of LacA activity assays.
format	article
author	Woo-Suk Jung Raushan Kumar Singh Jung-Kul Lee Cheol-Ho Pan
author_facet	Woo-Suk Jung Raushan Kumar Singh Jung-Kul Lee Cheol-Ho Pan
author_sort	Woo-Suk Jung
title	Crystal structure and substrate specificity of D-galactose-6-phosphate isomerase complexed with substrates.
title_short	Crystal structure and substrate specificity of D-galactose-6-phosphate isomerase complexed with substrates.
title_full	Crystal structure and substrate specificity of D-galactose-6-phosphate isomerase complexed with substrates.
title_fullStr	Crystal structure and substrate specificity of D-galactose-6-phosphate isomerase complexed with substrates.
title_full_unstemmed	Crystal structure and substrate specificity of D-galactose-6-phosphate isomerase complexed with substrates.
title_sort	crystal structure and substrate specificity of d-galactose-6-phosphate isomerase complexed with substrates.
publisher	Public Library of Science (PLoS)
publishDate	2013
url	https://doaj.org/article/71cf0dc8719f494a887e65d71da8ebbf
work_keys_str_mv	AT woosukjung crystalstructureandsubstratespecificityofdgalactose6phosphateisomerasecomplexedwithsubstrates AT raushankumarsingh crystalstructureandsubstratespecificityofdgalactose6phosphateisomerasecomplexedwithsubstrates AT jungkullee crystalstructureandsubstratespecificityofdgalactose6phosphateisomerasecomplexedwithsubstrates AT cheolhopan crystalstructureandsubstratespecificityofdgalactose6phosphateisomerasecomplexedwithsubstrates
_version_	1718421089369980928

Crystal structure and substrate specificity of D-galactose-6-phosphate isomerase complexed with substrates.

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