5WAS

Corynebacterium glutamicum Hydrolyzed Homoserine kinase

Summary for 5WAS

• Entry DOI: 10.2210/pdb5was/pdb
• Descriptor: Homoserine kinase, PHOSPHATE ION, ... (5 entities in total)
• Functional Keywords: corynebacterium glutamicum, homoserine kinase, l-threonine, l-homoserine, magnesium, transferase
• Biological source: Corynebacterium glutamicum; More
• Total number of polymer chains: 3
• Total formula weight: 33609.77

Authors

Petit, C.,Ronning, D.R. (deposition date: 2017-06-27, release date: 2018-02-07, Last modification date: 2023-10-04)

Primary citation

Petit, C.,Kim, Y.,Lee, S.K.,Brown, J.,Larsen, E.,Ronning, D.R.,Suh, J.W.,Kang, C.M.
Reduction of Feedback Inhibition in Homoserine Kinase (ThrB) ofCorynebacterium glutamicumEnhances l-Threonine Biosynthesis.
ACS Omega, 3:1178-1186, 2018

PubMed Abstract: l-Threonine is an important supplement in the food industry. It is currently produced through fermentation of but requires additional purification steps to remove endotoxin. To avoid these steps, it is desirable to use , a microorganism generally regarded as safe. Engineering of to increase production of l-threonine has mainly focused on gene regulation as well as l-threonine export or carbon flux depletion. In this study, we focus on the negative feedback inhibition produced by l-threonine on the enzyme homoserine kinase (ThrB). Although l-threonine binds to allosteric sites of aspartate kinase (LysC) and homoserine dehydrogenase (Hom), serving as a noncompetitive inhibitor, it acts as a competitive inhibitor on ThrB. This is problematic when attempting to engineer enzymes that are nonresponsive to increasing cellular concentrations of l-threonine. Using primary structure alignment as well as analysis of the ThrB (ThrB) active site in complex with l-threonine (inhibitor of ThrB) and l-homoserine (substrate of ThrB), a conserved active-site alanine residue (A20) in ThrB (ThrB) was predicted to be important for differential interactions with l-threonine and l-homoserine. Through site-directed mutagenesis, we show that one variant of ThrB, ThrB-A20G, retains wild-type enzymatic activity, with dramatically decreased feedback inhibition by l-threonine. Additionally, by solving the first X-ray crystal structure of homoserine kinase, we can confirm that the changes in l-threonine affinity to the ThrB-A20G active site derive from loss of van der Waals interactions.

PubMed: 30023797
DOI: 10.1021/acsomega.7b01597

Experimental method

X-RAY DIFFRACTION (1.799 Å)