Structure of formaldehyde dehydrogenase from Pseudomonas aeruginosa: the binary complex with the cofactor NAD⁺

Formaldehyde dehydrogenase (FDH) is a member of the zinc-containing medium-chain alcohol dehydrogenase family which oxidizes toxic formaldehyde to formate using NAD⁺ as an electron carrier. Three-dimensional structures have been reported for FDHs from several different species. Most FDHs are dependent on glutathione for catalysis, but the enzyme from Pseudomonas putida is an exception. In this structural communication, the recombinant production, crystallization and X-ray structure determination at 2.7 Å resolution of FDH from P. aeruginosa are described. Both the tetrameric assembly and the NAD⁺-binding mode of P. aeruginosa FDH are similar to those of P. putida FDH, which is in good agreement with the high sequence identity (87.97%) between these two proteins. Preliminary enzymatic kinetics studies of P. aeruginosa FDH also revealed a conserved glutathione-independent `ping-pong' mechanism of formaldehyde oxidization.