Serratia ‐based toxin cluster elements are associated with a type I fimbria

This article characterizes Sef fimbrial elements that have been observed to be consistently colocated with an ABC toxin complex (Tc) found in pathogenic Serratia species that infect the beetle larvae ofCostelytra giveni. This unique association between the fimbria and Tc has not been documented before in any known Tc system and raises questions about the high selective pressure for maintaining these fimbriae only in bacteria that encode Tcs. Our study also sought to characterize the structure and function of Sef fimbria using bioinformatics, cloning, and experimental approaches. AbstractA soil bacterium in theSerratia genus, carrying a 153  kb conjugative amber disease-associated plasmid (pADAP), is commercially exploited for population control of the New Zealand endemic pest beetleCostelytra giveni (Coleoptera: Scarabaeidae). The main insecticidal elements are an anti-feeding prophage and the Sep ABC toxin complex (Tc). Homologs of pADAP, encoding variant Tcs, convey different beetle disease phenotypes. To investigate the correlation between variable bioactivity and the Tc variant, 76Serratia plasmids were sequenced, resulting in the identification of four additionaltc variants. AllSerratia tc variants were found to be colocated with a conserved type 1sef fimbrial-like operon, indicating a conservedsef-tc genetic island not observed outside of theSerratia genus. The conserved co-location of the fimbrial andtc genes suggests the fimbriae somehow contribute to the lifestyle ...
Source: MicrobiologyOpen - Category: Microbiology Authors: Tags: ORIGINAL ARTICLE Source Type: research