The Tat pathway in Streptomyces lividans: interaction of Tat subunits and their role in translocation.

The twin-arginine translocation (Tat) pathway transports folded proteins across bacterial cytoplasmic membranes. The Tat system of Streptomyces lividans consists of TatA, TatB and TatC, unlike most Gram-positive bacteria, which only have TatA and TatC subunits. Interestingly, in S.

pspA overexpression in Streptomyces lividans improves both Sec- and Tat-dependent protein secretion.

Streptomyces is an interesting host for the secretory production of recombinant proteins because of its innate capacity to secrete proteins at high level in the culture medium. In this report, we evaluated the importance of the phage-shock protein A (PspA) homologue on the protein secretion yield in Streptomyces lividans. The PspA protein is supposed to play a role in the maintenance of the proton motive force (PMF).

Evaluation of TatABC overproduction on Tat- and Sec-dependent protein secretion in Streptomyces lividans.

The majority of bacterial proteins are exported across the cytoplasmic membrane via the Sec pathway, but also the more recently discovered twin-arginine translocation (Tat) route seems to play an important role for protein secretion in Streptomyces lividans in whose genome tatA, tatB and tatC have been identified. In the present work we showed that simultaneous overproduction of TatABC improved the Tat-dependent secretion capacity as could be concluded from the increased amount of secreted xylanase C, an exclusive Tat-dependent substrate. This result demonstrates that next to the availability of energy to drive secretion, also the number of translocases can be rate-limiting for Tat-dependent secretion.

Surface plasmon resonance-based interaction studies reveal competition of Streptomyces lividans type I signal peptidases for binding preproteins.

Type I signal peptidases (SPases) are responsible for the cleavage of signal peptides from secretory proteins. Streptomyces lividans contains four different SPases, denoted SipW, SipX, SipY and SipZ, having at least some differences in their substrate specificity. In this report in vitro preprotein binding/processing and protein secretion in single SPase mutants was determined to gain more insight into the substrate specificity of the different SPases and the underlying molecular basis.

Functional analysis of TatA and TatB in Streptomyces lividans.

Recently, genes encoding TatA, TatB, and TatC homologues were identified in Streptomyces lividans and the functionality of the twin-arginine translocation (Tat) pathway was demonstrated. Previously, we have shown that TatC is indispensable for Tat-dependent secretion in S. lividans.

Structural organization of the twin-arginine translocation system in Streptomyces lividans.

The twin-arginine translocation (Tat) system exports folded proteins across bacterial cytoplasmic membranes. Recently, genes encoding TatA, TatB and TatC homologues were identified in Streptomyces lividans and the functionality of the Tat pathway was demonstrated. Here, we have examined the localization and structural organization of the Tat components in S.

Comparison of the Sec and Tat secretion pathways for heterologous protein production by Streptomyces lividans.

Streptomyces is an interesting host for the secretory production of recombinant proteins because of its natural ability to secrete high levels of active proteins into the culture broth and the availability of extensive fermentation knowledge. In bacterial expression systems, heterologous protein secretion has, so far, almost exclusively been investigated using signal peptides that direct the secretion to the Sec pathway. In this study, we assessed the possibility of the Streptomyces lividans twin-arginine translocation (Tat) pathway to secrete the human proteins tumor necrosis factor (TNF) alpha and interleukin (IL) 10 by fusing the coding sequences of mature hTNFalpha and hIL10 to the twin-arginine signal peptides of S.