title: Ecological function of myroilysin, a novel bacterial M12 metalloprotease with elastinolytic activity and a synergistic role in collagen hydrolysis, in biodegradation of deep-sea high-molecular-weight organic nitrogen.
abstract: Nearly all high-molecular-weight (HMW) dissolved organic nitrogen and part of the particulate organic nitrogen in the deep sea are present in hydrolysis-resistant amides, and so far the mechanisms of biodegradation of these types of nitrogen have not been resolved. The M12 family is the second largest family in subclan MA(M) of Zn-containing metalloproteases and includes most enzymes from animals and only one enzyme (flavastacin) from a human-pathogenic bacterium (Flavobacterium meningosepticum). Here, we characterized the novel M12 protease myroilysin with elastinolytic activity and collagen-swelling ability from the newly described deep-sea bacterium Myroides profundi D25. Myroilysin is a monomer enzyme with 205 amino acid residues and a molecular mass of 22,936 Da. It has the same conserved residues at the four zinc ligands as astacin and very low levels of identity (<or=40%) to other metalloproteases, indicating that it is a novel metalloprotease belonging to subfamily M12A. Myroilysin had broad specificity and much higher elastinolytic activity than the bacterial elastinase pseudolysin. To our knowledge, it is the first reported elastase in the M12 family. Although it displayed very low activity with collagen, myroilysin had strong collagen-swelling ability and played a synergistic role with collagenase in collagen hydrolysis. It can be speculated that myroilysin synergistically interacts with other enzymes in its in situ biotic assemblage and that it may play an important role in the degradation of deep-sea HMW organic nitrogen.
authors.affiliation: State Key Lab of Microbial Technology, Marine Biotechnology Research Center, Shandong University, Jinan 250100, People's Republic of China.
authors.forename: Xiu-Lan
authors.initials: XL
authors.lastname: Chen
authors.forename: Bin-Bin
authors.initials: BB
authors.lastname: Xie
authors.forename: Fei
authors.initials: F
authors.lastname: Bian
authors.forename: Guo-Yan
authors.initials: GY
authors.lastname: Zhao
authors.forename: Hui-Lin
authors.initials: HL
authors.lastname: Zhao
authors.forename: Hai-Lun
authors.initials: HL
authors.lastname: He
authors.forename: Bai-Cheng
authors.initials: BC
authors.lastname: Zhou
authors.forename: Yu-Zhong
authors.initials: YZ
authors.lastname: Zhang
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001673:Biodegradation, Environmental; D003094:Collagen / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D017753:Ecosystem; D004549:Elastin / Q000378:metabolism*; D041965:Flavobacteriaceae / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D045726:Metalloproteases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009584:Nitrogen / Q000378:metabolism*; D012623:Seawater; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D003094:Collagen; D004549:Elastin; D045726:Metalloproteases; D009584:Nitrogen