PssA is required for α-amylase secretion in Antarctic Pseudoalteromonas haloplanktis

Abstract

Extracellular protein secretion is an essential feature in bacterial physiology. The ability to efficiently secrete diverse hydrolytic enzymes represents a key nutritional strategy for all bacteria, including micro-organisms living in extreme and hostile habitats, such as cold environments. However, little is known about protein secretion mechanisms in psychrophilic bacteria. In this study, the recombinant secretion of a cold-adapted α-amylase in the Antarctic Gram-negative Pseudoalteromonas haloplanktis TAC125 was investigated. By a combination of several molecular techniques, the function of the pssA gene was related to α-amylase secretion in this psychrophilic bacterium. Deletion of the pssA gene completely abolished amylase secretion without affecting the extracellular targeting of other substrates mediated by canonical secretion systems. The pssA gene product, PssA, is a multidomain lipoprotein, predicted to be localized in the bacterial outer membrane, and displaying three TPR (tetratricopeptide repeat) domains and two LysM modules. Based on functional annotation of these domains, combined with the experimental results reported herein, we suggest a role for PssA as a molecular adaptor, in charge of recruiting other cellular components required for specific α-amylase secretion. To the best of our knowledge, no proteins exhibiting the same domain organization have previously been linked to protein secretion.

Anti-Biofilm Activity of a Long-Chain Fatty Aldehyde from Antarctic Pseudoalteromonas haloplanktis TAC125 against Staphylococcus epidermidis Biofilm

“…The results of the RT-PCR experiments (Figure S3 ) showed that a PSHAb0219 gene transcription was clearly detected in the RNA samples extracted from P. haloplanktis TAC125 cells grown in both conditions. Several experiments were then attempted to delete the PSHAb0219 gene by using genetic tools for the creation of insertion/deletion mutants already available (Parrilli et al, 2010 ). However, these experiments were not successful probably due to the fact that PSHAb0219, in tested conditions, is likely to be an essential gene.…”

Proteomics of life at low temperatures: trigger factor is the primary chaperone in the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125

“…, 2004). Attempts to inactivate this gene in P. haloplanktis TAC125 were carried out using recently developed methods involving a suicide vector derived from a psychrophilic cryptic plasmid and successfully used to knockout non‐essential genes (Parrilli et al. , 2008; 2010).…”

“…In the mesophilic bacterium, the trigger factor gene is not essential for growth at any temperature (Deuerling et al, 1999;Kramer et al, 2004). Attempts to inactivate this gene in P. haloplanktis TAC125 were carried out using recently developed methods involving a suicide vector derived from a psychrophilic cryptic plasmid and successfully used to knockout non-essential genes (Parrilli et al, 2008;2010). It was, however, not possible to obtain TF deletion mutants of the Antarctic bacterium after recovery at either 4°C or 18°C.…”