The importance of PTS transporters in Lactobacillus johnsonii NCC 533 has been verified by studying gut persistence in vivo. Specifically, expression of a PTS transporter annotated as mannose-specific is required for the long-residence phenotype of L. johnsonii NCC 533 [15]. Genome sequencing of selected lactobacilli has enabled researchers to make additional conclusions about the traits and characteristics of these organisms. In 2006, the sequenced genomes of L. gasseri

ATCC 33323 and many other lactobacilli were released [16]. The currently available annotation of the L. gasseri ATCC 33323 genome describes numerous genes potentially involved in the uptake and metabolism of carbohydrates, yet the specific functions of these genes remain unknown. Our objective was to characterize PTS transporter functionality

in L. gasseri ATCC Fulvestrant datasheet 33323 using gene knockouts, bioinformatics, comparative carbohydrate utilization assays and transcript expression profiles. Results and Discussion Identification FK506 of PTS-Transported Carbohydrates As the most common method of carbohydrate utilization in some lactobacilli [17], the PTS transporters in L. gasseri ATCC 33323 were selected for further study. PTS transporters require a functional EI to import carbohydrates [18]. Additionally, some non-PTS carbohydrate transporters also require a functional PTS system for full transport activity [19, 20]. Insertional inactivation of EI in L. gasseri was performed to identify the carbohydrates which require a functional PTS system for utilization (Table 1). L. gasseri ATCC 33323 EI was only able to utilize 2 (D-glucose and D-maltose) of the 17 carbohydrates that the parent strain could utilize, indicating that transporters independent of the PTS system can import these two carbohydrates. The 15 carbohydrates that can be utilized by L. gasseri ATCC 33323 but not by L. gasseri ATCC 33323 EI are D-galactose, D-fructose, D-mannose, N-acetylglucosamine, amygdalin, arbutin, esculin ferric citrate, salicin, D-cellobiose, D-lactose, D-saccharose (sucrose), D-trehalose, amidon (starch), gentiobiose and D-tagatose.

These 15 carbohydrates are either (1) imported directly by a PTS transporter and/or (2) imported by a non-PTS carbohydrate Methamphetamine transporter that requires a functional PTS system. Examples of non-PTS transporters that require a functional PTS system to import sugars include LacS [19] and RafP [20]. Both LacS and RafP have a PTS IIA-glc domain (PF00358) fused to a permease domain. The PTS IIA-glc domain of these proteins is required for full transport activity. All PTS IIA domains identified in the Conserved Domain Database [21] for L. gasseri ATCC 33323 are a part of PTS transporters. Additionally, L. gasseri ATCC 33323 does not have homologs to LacS or RafP. Consequently, we can confirm that (1) L. gasseri ATCC 33323 does not have a LacS or RafP, and (2) L.