title: Mycoplasma agalactiae MAG_5040 is a Mg2+-dependent, sugar-nonspecific SNase recognised by the host humoral response during natural infection.
abstract: In this study the enzymatic activity of Mycoplasma agalactiae MAG_5040, a magnesium-dependent nuclease homologue to the staphylococcal SNase was characterized and its antigenicity during natural infections was established. A UGA corrected version of MAG_5040, lacking the region encoding the signal peptide, was expressed in Escherichia coli as a GST fusion protein. Recombinant GST-MAG_5040 exhibits nuclease activity similar to typical sugar-nonspecific endo- and exonucleases, with DNA as the preferred substrate and optimal activity in the presence of 20 mM MgCl2 at temperatures ranging from 37 to 45°C. According to in silico analyses, the position of the gene encoding MAG_5040 is consistently located upstream an ABC transporter, in most sequenced mycoplasmas belonging to the Mycoplasma hominis group. In M. agalactiae, MAG_5040 is transcribed in a polycistronic RNA together with the ABC transporter components and with MAG_5030, which is predicted to be a sugar solute binding protein by 3D modeling and homology search. In a natural model of sheep and goats infection, anti-MAG_5040 antibodies were detected up to 9 months post infection. Taking into account its enzymatic activity, MAG_5040 could play a key role in Mycoplasma agalactiae survival into the host, contributing to host pathogenicity. The identification of MAG_5040 opens new perspectives for the development of suitable tools for the control of contagious agalactia in small ruminants.
authors.affiliation: Dipartimento di Medicina Veterinaria, Università degli Studi di Sassari, Sassari, Italy.
authors.forename: Carla
authors.initials: C
authors.lastname: Cacciotto
authors.forename: Maria Filippa
authors.initials: MF
authors.lastname: Addis
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Coradduzza
authors.forename: Laura
authors.initials: L
authors.lastname: Carcangiu
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Nuvoli
authors.forename: Gessica
authors.initials: G
authors.lastname: Tore
authors.forename: Gian Mario
authors.initials: GM
authors.lastname: Dore
authors.forename: Daniela
authors.initials: D
authors.lastname: Pagnozzi
authors.forename: Sergio
authors.initials: S
authors.lastname: Uzzau
authors.forename: Bernardo
authors.initials: B
authors.lastname: Chessa
authors.forename: Marco
authors.initials: M
authors.lastname: Pittau
authors.forename: Alberto
authors.initials: A
authors.lastname: Alberti
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology; D003001:Cloning, Molecular; D019295:Computational Biology; D015964:Gene Expression Regulation, Bacterial; D006041:Goats / Q000382:microbiology; D056724:Immunity, Humoral; D008274:Magnesium / Q000378:metabolism*; D008836:Micrococcal Nuclease / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D009175:Mycoplasma Infections / Q000276:immunology*; D045644:Mycoplasma agalactiae / Q000235:genetics / Q000276:immunology / Q000378:metabolism* / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D012756:Sheep / Q000382:microbiology; D013379:Substrate Specificity
chemical_list: D000942:Antigens, Bacterial; D008836:Micrococcal Nuclease; D008274:Magnesium