Prophage 2 of strain

Prophage 2 of strain activator Ivacaftor T5T is a Mu-like bacteriophage, not present in strain DSM 17395. It was previously shown that strain T5T produces two different AHLs, i.e. C18-en-HSL and N-3-hydroxydecanoyl-homoserine lactone (3OHC10-HSL) [76]. In P. inhibens strain DSM 17395 TDA and pigment production are regulated via a pgaR-pgaI QS system [47]. The AHL synthase encoding gene pgaI in DSM 17395 is responsible for the production of 3OHC10-HSL. In the genome of strain T5T we found a homologous system probably coding for the 3OHC10-HSL producing AHL synthase (Inhi_2120, homolog to pgaI) and the respective regulator (Inhi_2121, homologous to pgaR) (Figure 3, QS system I). Thus TDA production in strain T5T might also be regulated by a QS system. In addition, two further QS systems (QS system II and III; Figure 3) were found on the chromosome of T5T.

System II is formed by the genes Inhi_0506 and _0507 and is located in the prophage region 2. Orthologs for these QS system genes are also present in P. inhibens strain DSM 24588 (PGA2_c18960 and PGA2_c18970) but absent in strain DSM 17395. QS system III consists of the genes Inhi_1819 and _1820 and is unique for strain T5T compared to P. inhibens DSM 17395 and DSM 24588. It is also located in the potential prophage 1 region (Fig. 3). A homologous system was found in the genome of Phaeobacter caeruleus DSM 24564T and the neighboring genes show a high synteny. The location in the prophage region and the high synteny to the system of P. caeruleus suggest a possible gene transfer of this QS system via a bacteriophage.

The functions of QS system II and III are currently unknown, but it is likely that the compound C18-en-HSL is produced by one of those systems. Two functions were suggested that can possibly be used as unique chemotaxonomic markers for the species P. inhibens within the Roseobacter clade [3]. The genes coding for the first of these functions are located on the chromosome and are involved in cell wall development and surface attachment [dltA encoding a D-alanine-poly(phosphoribitol) ligase involved in biosynthesis of D-alanyl-lipoteichoic acid]. The second unique function is the biosynthesis and transport of iron-chelating siderophores, and the encoding genes are located on the plasmid pPGA1_78 and pPGA2_95, respectively. These two clusters are also present in the genome of strain T5T.

The siderophore gene cluster (Inhi_3924 �C Inhi_3928) is located on the 78 kb plasmid (Fig. 3) and the dltA gene cluster (Inhi_1065 – Inhi_1086) is located on the chromosome (Fig. 3). Screenings in the newly available Roseobacter genomes showed that Leisingera methylohalidivorans DSM 14336 [42] and Leisingera aquimarina DSM 24565 [41] also harbor the genes for siderophore synthesis. The uniqueness of the dltA gene cluster within Batimastat the species P. inhibens, however, remains and can be used as chemotaxonomic marker.

Leave a Reply

Your email address will not be published. Required fields are marked *


You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>