Learn More
SecA, the dimeric ATPase subunit of bacterial protein translocase, catalyses translocation during ATP-driven membrane cycling at SecYEG. We now show that the SecA protomer comprises two structural modules: the ATPase N-domain, containing the nucleotide binding sites NBD1 and NBD2, and the regulatory C-domain. The C-domain binds to the N-domain in each(More)
SecA, the motor subunit of bacterial polypeptide translocase, is an RNA helicase. SecA comprises a dimerization C-terminal domain fused to an ATPase N-terminal domain containing conserved DEAD helicase motifs. We show that the N-terminal domain is organized like the motor core of DEAD proteins, encompassing two subdomains, NBD1 and IRA2. NBD1, a rigid(More)
Recognition of signal sequences by cognate receptors controls the entry of virtually all proteins to export pathways. Despite its importance, this process remains poorly understood. Here, we present the solution structure of a signal peptide bound to SecA, the 204 kDa ATPase motor of the Sec translocase. Upon encounter, the signal peptide forms an(More)
Extra-cytoplasmic polypeptides are usually synthesized as 'preproteins' carrying amino-terminal, cleavable signal peptides and secreted across membranes by translocases. The main bacterial translocase comprises the SecYEG protein-conducting channel and the peripheral ATPase motor SecA. Most proteins destined for the periplasm and beyond are exported(More)
More than one-third of cellular proteomes traffic into and across membranes. Bacteria have invented several sophisticated secretion systems that guide various proteins to extracytoplasmic locations and in some cases inject them directly into hosts. Of these, the Sec system is ubiquitous, essential and by far the best understood. Secretory polypeptides are(More)
Type III protein secretion (TTS) is catalyzed by translocases that span both membranes of Gram-negative bacteria. A hydrophilic TTS component homologous to F1/V1-ATPases is ubiquitous and essential for secretion. We show that hrcN encodes the putative TTS ATPase of Pseudomonas syringae pathovar phaseolicola and that HrcN is a peripheral protein that(More)
The gene encoding a novel xyloglucanase (Xeg) belonging to family 74 glycoside hydrolases was isolated from a Jonesia sp. strain through functional screening in Escherichia coli. The encoded xyloglucanase is a protein of 972 aminoacyl residues with a 23 residue aminoterminal signal peptide. Over-expression of Xeg in B. subtilis or E. coli failed. In(More)
SecA, the dimeric ATPase subunit of protein translocase, contains a DEAD helicase catalytic core that binds to a regulatory C-terminal domain. We now demonstrate that IRA1, a conserved helix-loop-helix structure in the C-domain, controls C-domain conformation through direct interdomain contacts. C-domain conformational changes are transmitted to the DEAD(More)
SecA, the preprotein translocase ATPase is built of an amino-terminal DEAD helicase motor domain bound to a regulatory C-domain. SecA recognizes mature and signal peptide preprotein regions. We now demonstrate that the amino-terminal 263 residues of the ATPase subdomain of the DEAD motor are necessary and sufficient for high affinity signal peptide binding.(More)
All cells must traffic proteins across their membranes. This essential process is responsible for the biogenesis of membranes and cell walls, motility and nutrient scavenging and uptake, and is also involved in pathogenesis and symbiosis. The translocase is an impressively dynamic nanomachine that is the central component which catalyses transmembrane(More)