Involvement of a quinoprotein (PQQ-containing) alcohol dehydrogenase in the degradation of polypropylene glycols by the bacterium Stenotrophomonas maltophilia

Abstract

Previous work has shown that when the bacterium Stenotrophomonas maltophilia is grown on polypropylene glycol, different dye-linked polypropylene glycol dehydrogenase (PPG-DH) activities are induced during growth. Here the purification and characterization of the dehydrogenase activity induced in the stationary phase, and present in the periplasmic space, is described. The homogeneous enzyme preparation obtained consists of a homodimeric protein with a molecular mass of about 123 kDa and an isoelectric point of 5.9. The cofactor of the enzyme appeared to be pyrroloquinoline quinone (PQQ), no heme c was present, and holo-enzyme contained two PQQ molecules per enzyme molecule. In these respects, PPG-DH described here is similar to already known quinoprotein alcohol dehydrogenases, but in other respects, it is different. Therefore, it is suggested that PPG-DH could be a new type of quinoprotein alcohol dehydrogenase. Based on its strong preference for polyols, PPG-DH seems well fitted to carry out the first step in the degradation of PPGs, synthetic polymers containing a variety of hydroxyl groups.

The Relationship Between the Chemical Structure of Poly(alkylene glycol)s and Their Aerobic Biodegradability in an Aqueous Environment

“…The presence of 7-day lag phases for PPG 7P and PAG TG 600E degradation observed in our test substantiates the theory formulated by Kawai and Tachibana et al [11,12]. They state that PEG polymers are biodegraded by the micro-organisms of the activated sludge, which utilise constitutive enzymes, namely alcohol and aldehyde dehydrogenases; these enzymes have been identified in the bacteria of the activated sludge used in PEG biodegradation tests.…”

“…However, in the past two decades, investigations have been reported that are devoted to the assessment of PEG biodegradability, yet rarely do they address PPG biodegradability [11][12][13][14][15][16][17]; these investigations have also reported on the determination of mechanisms that rule PEG or PPG biodegradation. There are only a few reports on the biodegradability of copolymeric PAGs, and there is a lack of data on its dependence on the chemical structure of these polymers [1,18,19].…”

Polymorphic Mutation Frequencies of Clinical and Environmental Stenotrophomonas maltophilia Populations

“…Some S. maltophilia strains have been used for bioremediation (13,24,73) or bioaugmentation (37). However, besides its environmental origin and potential relevance for biotechnological purposes, S. maltophilia is also a relevant human opportunistic pathogen (44) associated with a broad spectrum of clinical syndromes, such as bacteremia (79,81), endocarditis (18), infection in cancer patients (1), and respiratory tract infections, including those suffered by cystic fibrosis (CF) patients (72,77).…”

Cloning and expression of the gene for periplasmic poly(vinyl alcohol) dehydrogenase from Sphingomonas sp. strain 113P3, a novel-type quinohaemoprotein alcohol dehydrogenase

“…EbN1 conserved a haem c-binding domain, a likely PQQ-binding amino acids motif and a superbarrel domain made up of eight beta-sheets (called W1-W8) similar to PVADHs from three PVA-utilizing strains, but those from Xanthomonas species conserved a likely PQQ-binding amino acids motif and a superbarrel domain, but lacked a haem-binding domain. On the other hand, PPG dehydrogenase from Stenotrophomonas maltophilia was a type I Q-ADH and oxidized PVA (41 %) as well as PPG (diol type) 700 (100 %) (Tachibana et al, 2003). PVADHs from Xanthomonas species are thought to be type I Q-ADHs similar to PPG dehydrogenase.…”

“…2). Peaks indicated the presence of haem c and an electron flow from PQQ to haem c. The enzyme had higher activity toward PPGs (137 % for PPG 400 and 172 % for PPG 700) than PVA 117 (100 %), which corresponded to the activity of PPG dehydrogenase on PPG (diol type) 700 (100 %) and PVA 500 (41 %) (Tachibana et al, 2003). The enzyme also acted slightly on glycols such as 2,4-pentanediol (1?6 %), 1,3-cyclohexanediol (8?4 %) and 1,3-butanediol (1?0 %), but not at all on secondary alcohols (2-pentanol, 2-hexanol and 4-heptanol) and primary alcohols (methanol to 1-pentanol).…”