Characterization of YqjM, an Old Yellow Enzyme Homolog from Bacillus subtilis Involved in the Oxidative Stress Response

Abstract

In this paper, we demonstrate that a protein from Bacillus subtilis (Yq jM) shares many characteristic biochemical properties with the homologous yeast Old Yellow Enzyme (OYE); the enzyme binds FMN tightly but noncovalently, preferentially uses NADPH as a source of reducing equivalents, and forms charge transfer complexes with phenolic compounds such as p-hydroxybenzaldehyde. Like yeast OYE and other members of the family, Yq jM catalyzes the reduction of the double bond of an array of ␣,␤-unsaturated aldehydes and ketones including nitroester and nitroaromatic compounds. Although yeast OYE was the first member of this family to be discovered in 1933 and was the first flavoenzyme ever to be isolated, the physiological role of the family still remains obscure. The finding that ␣,␤-unsaturated compounds are substrates provoked speculation that the OYE family might be involved in reductive degradation of xenobiotics or lipid peroxidation products. Here, for the first time, we demonstrate on the protein level that whereas Yq jM shows a basal level of expression in B. subtilis, the addition of the toxic xenobiotic, trinitrotoluene, leads to a rapid induction of the protein in vivo denoting a role in detoxification. Moreover, we show that Yq jM is rapidly induced in response to oxidative stress as exerted by hydrogen peroxide, demonstrating a potential physiological role for this enigmatic class of proteins.

Ligand-induced Conformational Changes in the Capping Subdomain of a Bacterial Old Yellow Enzyme Homologue and Conserved Sequence Fingerprints Provide New Insights into Substrate Binding

“…Because SYE1 exhibits a preference for NADH, this theory cannot be extended to all OYE homologues. When we compare the utilization of reducing power among OYE homologues, we find that the ones preferring NADPH accepted both NADPH and NADH, but with a preference for the former (18,31,37,41,45). On the other hand, OYEs that use NADH cannot accept NADPH.…”

“…The OYE family has grown steadily in recent years and now features the bacterial nitro-ester reductases PETN reductase (8), glycerol trinitrate reductase (9), XenA/B reductase (10), the bacterial morphinone reductase (11), the YqjM from Bacillus subtilis (41), the plant oxophytodienoic acid reductases (12,13), several yeast OYEs (14 -17), and an enzyme involved in prostaglandin synthesis in Trypanosoma cruzi (18). Although these enzymes originate from different organisms and catalyze different reactions, they share several common functional characteristics.…”

The Role of Oxophytodienoate Reductases in the Detoxification of the Explosive 2,4,6-Trinitrotoluene by Arabidopsis

“…The OPRs share similarity with the Old Yellow Enzyme family, a group of flavoenzymes that has been repeatedly associated with the transformation of explosives (Binks et al, 1996;Schaller and Weiler, 1997;Snape et al, 1997;Basran et al, 1998;French et al, 1998;Blehert et al, 1999;Pak et al, 2000;Fitzpatrick et al, 2003;Williams et al, 2004). Studies also indicate that Old Yellow Enzyme homologs function as antioxidants, detoxifying the breakdown products of lipid peroxidation and other toxic electrophilic compounds (Kohli and Massey, 1998;Williams and Bruce, 2002;Fitzpatrick et al, 2003;Trotter et al, 2006).…”

“…Studies also indicate that Old Yellow Enzyme homologs function as antioxidants, detoxifying the breakdown products of lipid peroxidation and other toxic electrophilic compounds (Kohli and Massey, 1998;Williams and Bruce, 2002;Fitzpatrick et al, 2003;Trotter et al, 2006). This oxidative stress could result from exposure to xenobiotics including TNT, wounding, or pathogen attack.…”

Structural insights into stereospecific reduction of α, β-unsaturated carbonyl substrates by old yellow enzyme from Gluconobacter oxydans

“…Although many OYE family members have been identified from yeast, bacteria, and plants recently [9][10][11][12][13][14][15][16][17][18] ) and their potential metabolic functions have been suggested, the exact physiological functions of OYEs are largely unknown. 11,[19][20][21] Gluconobacter oxydans is regarded as one of the most important industrial bacteria due to its unique ability to incompletely oxidize a wide range of carbohydrates and alcohols with excellent efficiency and regio-, stereo-, and enantio-selectivity under natural conditions. [22][23][24][25][26][27][28] Genome sequence analysis of G. oxydans has revealed 12 putative cytosolic flavinassociated proteins.…”