Translocation of proteins across the cell envelope of Gram-positive bacteria

Abstract

In contrast to Gram-negative bacteria, secretory proteins of Gram-positive bacteria only need to traverse a single membrane to enter the extracellular environment. For this reason, Gram-positive bacteria (e.g. various Bacillus species) are often used in industry for the commercial production of extracellular proteins that can be produced in yields of several grams per liter culture medium. The central components of the main protein translocation system (Sec system) of Gram-negative and Gram-positive bacteria show a high degree of conservation, suggesting similar functions and working mechanisms. Despite this fact, several differences can be identified such as the absence of a clear homolog of the secretion-specific chaperone SecB in Gram-positive bacteria. The now available detailed insight into the organization of the Gram-positive protein secretion system and how it differs from the well-characterized system of Escherichia coli may in the future facilitate the exploitation of these organisms in the high level production of heterologous proteins which, so far, is sometimes very inefficient due to one or more bottlenecks in the secretion pathway. In this review, we summarize the current knowledge on the various steps of the protein secretion pathway of Gram-positive bacteria with emphasis on Bacillus subtilis, which during the last decade, has arisen as a model system for the study of protein secretion in this industrially important class of microorganisms.

Phage display reveals 52 novel extracellular and transmembrane proteins from Lactobacillus reuteri DSM 20016T

“…For prediction of signal sequences, the SignalP V2.0 program for Gram-positive bacteria (Nielsen et al, 1997) (http://www.cbs.dtu.dk) was utilized. The signal sequences were verified manually to confirm the presence of the N-, C-and Hregions (van Wely et al, 2001). In addition, translation initiation sequences (reviewed by Kozak, 1999) were searched for manually.…”

“…These are the amino-terminal (N-) region with positively charged amino acids; the central hydrophobic (H-) region; and the carboxy-terminal (C-) region containing the signal-peptide cleavage-site. After translocation, signal peptidases separate the signal peptide from the protein (van Wely et al, 2001), or alternatively the signal peptide is inserted into the plasma membrane as a signal anchor (Martoglio & Dobberstein, 1998).…”

Regulation of expression of type I signal peptidases in Listeria monocytogenes

“…During, or shortly after, the translocation process, most signal peptides are removed by signal peptidases (SPases), which is a prerequisite for the release of secretory proteins from the extracytoplasmic side of the membrane (Paetzel et al, 2000). Thus, SPases play a key role in the transport of protein across membranes in all living organisms (van Wely et al, 2001). In Grampositive bacteria, the exported proteins are either secreted into the medium, or they remain associated by various means with the bacterial envelope.…”

Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus in Finland

“…Beneath the capsule S. aureus harbors a typical gram positive cell wall (86). The gram positive cell wall differs from that of gram negative bacteria in two major characteristics: a gram positive cell wall has a thicker and highly crosslinked peptidoglycan layer, and it lacks the outer membrane (12,18,220,287) (Figure 1). …”