6B2O

LarE, a sulfur transferase involved in synthesis of the cofactor for lactate racemase, C176A variant

Summary for 6B2O

• Entry DOI: 10.2210/pdb6b2o/pdb
• Related: 6B2M
• Descriptor: ATP-utilizing enzyme of the PP-loopsuperfamily, PHOSPHATE ION, SULFATE ION, ... (4 entities in total)
• Functional Keywords: lar, sulfur transferase, lare, ampylation, hexamer, trimer, pp-loop, atp, magnesium, atp pyrophophatase domain, lactate, lactate racemization, lactate racemase, cysteine to alanine, transferase
• Biological source: Lactobacillus plantarum
• Total number of polymer chains: 6
• Total formula weight: 191170.36

Authors

Fellner, M.,Hausinger, R.P.,Hu, J. (deposition date: 2017-09-20, release date: 2018-09-05, Last modification date: 2023-10-04)

Primary citation

Fellner, M.,Rankin, J.A.,Desguin, B.,Hu, J.,Hausinger, R.P.
Analysis of the Active Site Cysteine Residue of the Sacrificial Sulfur Insertase LarE from Lactobacillus plantarum.
Biochemistry, 57:5513-5523, 2018

PubMed Abstract: LarE from Lactobacillus plantarum is an ATP-dependent sulfur transferase that sacrifices its Cys176 sulfur atom to form a dehydroalanine (Dha) side chain during biosynthesis of the covalently linked nickel-pincer nucleotide (NPN) cofactor (pyridinium 3-thioamide-5-thiocarboxylic acid mononucleotide) of lactate racemase. Coenzyme A (CoA) stabilizes LarE and forms a CoA-Cys176 mixed disulfide with the protein. This study presents the crystal structure of the LarE/CoA complex, revealing protein interactions with CoA that mimic those for binding ATP. CoA weakly inhibits LarE activity, and the persulfide of CoA is capable of partially regenerating functional LarE from the Dha176 form of the protein. The physiological relevance of this cycling reaction is unclear. A new form of LarE was discovered, an NPN-LarE covalent adduct, explaining prior results in which activation of the lactate racemase apoprotein required only the isolated LarE. The crystal structure of the inactive C176A variant revealed a fold essentially identical to that of wild-type LarE. Additional active site variants of LarE were created and their activities characterized, with all LarE variants analyzed in terms of the structure. Finally, the L. plantarum LarE structure was compared to a homology model of Thermoanaerobacterium thermosaccharolyticum LarE, predicted to contain three cysteine residues at the active site, and to other proteins with a similar fold and multiple active site cysteine residues. These findings suggest that some LarE orthologs may not be sacrificial but instead may catalyze sulfur transfer by using a persulfide mechanism or from a labile site on a [4Fe-4S] cluster at this position.

PubMed: 30157639
DOI: 10.1021/acs.biochem.8b00601

Experimental method

X-RAY DIFFRACTION (2.35 Å)