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. In the present work, we demonstrate that as TatB, S. lividans TatA is important but not essential for efficient secretion of xylanase C and tyrosinase. The results presented here indicate that in the presence of TatC, still partially functional translocation systems composed of TatAC or TatBC can be formed, suggesting that TatA and TatB have at least partially overlapping activities. However, the dissimilar effect caused by a tatA deletion or a tatB deletion on Tat-dependent secretion together with the fact that TatA cannot fully functionally substitute TatB and vice versa indicates that in S. lividans TatA and TatB are not functionally equivalent. Interestingly, soluble GST-tagged TatA and TatB were able to specifically bind Tat-dependent preproteins. The ability to bind Tat-dependent preproteins together with their cytoplasmic localization in S. lividans strongly suggests that both TatA and TatB, independently or associated, serve to recruit Tat-dependent preproteins to the translocase.
De Keersmaeker
Sophie
S
Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium. Sophie.Dekeersmaeker@rega.kuleuven.be
Van Mellaert
Lieve
L
Lammertyn
Elke
E
Vrancken
Kristof
K
Anné
Jozef
J
Geukens
Nick
N
D000595:Amino Acid Sequence; D001483:Base Sequence; D015153:Blotting, Western; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D005798:Genes, Bacterial; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010641:Phenotype; D010957:Plasmids; D017386:Sequence Homology, Amino Acid; D048170:Streptomyces lividans / Q000235:genetics / Q000378:metabolism*; D020349:Surface Plasmon Resonance
D017931:DNA Primers; D026901:Membrane Transport Proteins