title: Yersinia enterocolitica and Photorhabdus asymbiotica β-lactamases BlaA are exported by the twin-arginine translocation pathway.
abstract: In general, β-lactamases of medically important Gram-negative bacteria are Sec-dependently translocated into the periplasm. In contrast, β-lactamases of Mycobacteria spp. (BlaC, BlaS) and the Gram-negative environmental bacteria Stenotrophomonas maltophilia (L2) and Xanthomonas campestris (Bla(XCC-1)) have been reported to be secreted by the twin-arginine translocation (Tat) system. Yersinia enterocolitica carries 2 distinct β-lactamase genes (blaA and blaB) encoding BlaA(Ye) and the AmpC-like β-lactamase BlaB, respectively. By using the software PRED-TAT for prediction and discrimination of Sec from Tat signal peptides, we identified a functional Tat signal sequence for Yersinia BlaA(Ye). The Tat-dependent translocation of BlaA(Ye) could be clearly demonstrated by using a Y. enterocolitica tatC-mutant and cell fractionation. Moreover, we could demonstrate a unique unusual temperature-dependent activity profile of BlaA(Ye) ranging from 15 to 60 °C and a high 'melting temperature' (T(M)=44.3°) in comparison to the related Sec-dependent β-lactamase TEM-1 (20-50°C, T(M)=34.9 °C). Strikingly, the blaA gene of Y. enterocolitica is present in diverse environmental Yersinia spp. and a blaA homolog gene could be identified in the closely related Photorhabdus asymbiotica (BlaA(Pa); 69% identity to BlaA(Ye)). For BlaA(Pa) of P. asymbiotica, we could also demonstrate Tat-dependent secretion. These results suggest that Yersinia BlaA-related β-lactamases may be the prototype of a large Tat-dependent β-lactamase family, which originated from environmental bacteria.
authors.affiliation: Max von Pettenkofer Institute for Hygiene and Medical Microbiology, Ludwig Maximilians University of Munich, D-80336 Munich, Germany.
authors.forename: Eva-Maria
authors.initials: EM
authors.lastname: Schriefer
authors.forename: Stephanie
authors.initials: S
authors.lastname: Hoffmann-Thoms
authors.forename: Franz X
authors.initials: FX
authors.lastname: Schmid
authors.forename: Annika
authors.initials: A
authors.lastname: Schmid
authors.forename: Jürgen
authors.initials: J
authors.lastname: Heesemann
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001120:Arginine / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D008826:Microbial Sensitivity Tests; D009154:Mutation; D015688:Oncogene Protein pp60(v-src); D020637:Photorhabdus / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D021382:Protein Sorting Signals; D055550:Protein Stability; D021381:Protein Transport; D011994:Recombinant Proteins; D016415:Sequence Alignment; D012984:Software; D013696:Temperature; D015009:Yersinia Infections / Q000382:microbiology*; D015008:Yersinia enterocolitica / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D001618:beta-Lactamases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D021382:Protein Sorting Signals; D011994:Recombinant Proteins; D001120:Arginine; D015688:Oncogene Protein pp60(v-src); D001618:beta-Lactamases