Deciphering a unique biotin scavenging pathway with redundant genes in the probiotic bacterium Lactococcus lactis

Abstract

Biotin protein ligase (BPL) is widespread in the three domains of the life. The paradigm BPL is the Escherichia coli BirA protein, which also functions as a repressor for the biotin biosynthesis pathway. Here we report that Lactococcus lactis possesses two different orthologues of birA (birA1_LL and birA2_LL). Unlike the scenario in E. coli, L. lactis appears to be auxotrophic for biotin in that it lacks a full biotin biosynthesis pathway. In contrast, it retains two biotin transporter-encoding genes (bioY1_LL and bioY2_LL), suggesting the use of a scavenging strategy to obtain biotin from the environment. The in vivo function of the two L. lactis birA genes was judged by their abilities to complement the conditional lethal E. coli birA mutant. Thin-layer chromatography and mass spectroscopy assays demonstrated that these two recombinant BirA proteins catalyze the biotinylation reaction of the acceptor biotin carboxyl carrier protein (BCCP), through the expected biotinoyl-AMP intermediate. Gel shift assays were used to characterize bioY1_LL and BirA1_LL. We also determined the ability to uptake 3H-biotin by L. lactis. Taken together, our results deciphered a unique biotin scavenging pathway with redundant genes present in the probiotic bacterium L. lactis.

Functional dissection and modulation of the BirA protein for improved autotrophic growth of gas‐fermenting Clostridium ljungdahlii

“…Among these TFs, BirA has been known to be an important bifunctional protein with both the biotin protein ligase (BPL) activity and biotin operon repressor function in some model bacteria, such as Escherichia coli , Bacillus subtilis and Staphylococcus aureus (Weaver et al ., 2001; da Costa et al ., 2012; Feng et al ., 2014). As the ligase, BirA is responsible for the biotinylation of acetyl‐CoA carboxylase (ACC) and pyruvate carboxylase (PYC), thereby significantly influencing the activity of these two enzymes (Li and Sousa, 2012; Peters‐Wendisch et al ., 2012); as the biotin operon repressor, BirA regulates biotin synthesis and uptake and thus enables the in vivo biotin homeostasis (Ye et al ., 2016; Zhang et al ., 2016). Additionally, a recent study revealed that BirA can interact with other regulators to realize a wide regulatory scope in enterohaemorrhagic E. coli (Yang et al ., 2015).…”

Molecular Basis of BioJ, a Unique Gatekeeper in Bacterial Biotin Synthesis

“…Plants and certain microorganisms possess the ability of de novo biotin synthesis, whereas mammals and birds do not (Cronan, 2014). Therefore, it is reasonable that a scavenging/uptake pathway of biotin from food is present in animals or from the inhabiting niche in the biotin auxotrophic microorganisms (Hebbeln et al., 2007) (like Lactococcus [Zhang et al., 2016] and Streptococcus [Ye et al., 2016]). The most of knowledge on biotin synthesis is from studies with the model bacterium Escherichia coli (Cronan, 2014).…”

Crystal structure and acetylation of BioQ suggests a novel regulatory switch for biotin biosynthesis in Mycobacterium smegmatis

“…Intriguingly, the BioC [S‐adenosyl‐L‐methionine(SAM)‐dependent methyltransferase]‐containing organisms have different counterparts to replace the paradigm BioH, a promiscuous member of α/β hydrolase super family, including BioJ in Francisella (Feng et al, ), BioG of Haemophilus (Shi et al, ), BioK in Prochlorococcus (Shapiro et al, ), and BioV from Helicobacter (Bi et al, ). In addition, microorganisms [like the human isolate of Streptococcus suis (Ye et al, ) and the probiotic bacterium Lactococcus suis (Zhang et al, )] also have developed the BioY transporter‐dependent uptake system to scavenge trace amount of biotin from its inhabiting niches for survival (Rodionov et al, ).…”