3FQA

Gabaculien complex of gabaculine resistant GSAM version

Summary for 3FQA

• Entry DOI: 10.2210/pdb3fqa/pdb
• Related: 2HP1 2HP2 3FQ7 3FQ8
• Descriptor: Glutamate-1-semialdehyde 2,1-aminomutase, 4'-DEOXY-4'-AMINOPYRIDOXAL-5'-PHOSPHATE, 3-AMINOBENZOIC ACID, ... (4 entities in total)
• Functional Keywords: drug resistance, microevilution, integrated approach, chlorophyll biosynthesis, cytoplasm, isomerase, porphyrin biosynthesis, pyridoxal phosphate
• Biological source: Synechococcus elongatus PCC 6301
• Cellular location: Cytoplasm (Potential): P24630
• Total number of polymer chains: 2
• Total formula weight: 91773.46

Authors

Stetefeld, J. (deposition date: 2009-01-07, release date: 2009-11-24, Last modification date: 2023-09-06)

Primary citation

Orriss, G.L.,Patel, T.R.,Sorensen, J.,Stetefeld, J.
Absence of a catalytic water confers resistance to the neurotoxin gabaculine.
Faseb J., 24:404-414, 2010

PubMed Abstract: Gabaculine is a potent inhibitor of the vitamin B6-dependent key enzyme in chlorophyll biosynthesis, glutamate-1-semialdehyde aminomutase (GSAM). The inhibition effect is caused by an enzymatic deprotonation of the neurotoxin and requires the aldimine (PLP) form of the cofactor at the active site. In this study, we show that a single-point mutation confers resistance to gabaculine. A combined functional and structural analysis of wild-type GSAM in complex with gabaculine and the GSAM(M248I) form allowed us to decipher in atomic detail the molecular basis of this unique resistance. Interestingly, the gabaculine tolerance is caused by the absence of an essential water molecule that has a dual functional role. It serves as a nucleophilic shuttle for the hydroxyl anion along the reaction pathway and holds active-site Lys273 in a catalytically competent conformation. The single-point mutant is not able to fix this catalytic water between the beta-branched side chain of Ile248 and Lys273. As a consequence, the mutant enzyme is trapped in a gabaculine-insensitive but still enzymatically active amine (PMP) form.

PubMed: 19786580
DOI: 10.1096/fj.09-138297

Experimental method

X-RAY DIFFRACTION (2.35 Å)