ABSTRACT
The isolation of cellulosomes from clostridial sources has been extensively studied; however, the isolation of cellulosomes from facultative soil anaerobes of the family Bacillaceae is not as well characterized. The Bacillus cellulosome (celluloxylanosome) essentially consists of two complex components: C-I and C-II. This multi-component complex enables Bacillus to degrade a variety of carbonaceous compounds as it is composed of several enzymes, such as cellulases, xylanases and other degradative enzymes. The cellulosomal cellulases from Bacillus megaterium were purified using cellulose affinity chromatography, followed by Sepharose 4B gel filtration chromatography. The objective of this investigation was to establish the effect of sulfate and sulfide on cellulosomal 'cellulase' activity. An increase in sulfide concentration led to a general enhancement of cellulosomal-associated cellulolytic activity, whereas an increase in sulfate concentration resulted in an inhibition of the cellulosome-associated cellulolytic activity.
Subject(s)
Bacillus/drug effects , Bacterial Proteins/metabolism , Cellulase/metabolism , Cellulosomes/drug effects , Sulfur Compounds/pharmacology , Bacillus/enzymology , Bacterial Proteins/chemistry , Cellulose/metabolism , Cellulosomes/enzymology , Cellulosomes/physiology , Glycoside Hydrolases/genetics , Glycoside Hydrolases/isolation & purification , Glycoside Hydrolases/metabolismABSTRACT
In the course of evolution, Gram-positive bacteria, defined here as prokaryotes from the domain Bacteria with a cell envelope composed of one biological membrane (monodermita) and a cell wall composed at least of peptidoglycan and covalently linked teichoic acids, have developed several mechanisms permitting to a cytoplasmic synthesized protein to be present on the bacterial cell surface. Four major types of cell surface displayed proteins are currently recognized: (i) transmembrane proteins, (ii) lipoproteins, (iii) LPXTG-like proteins and (iv) cell wall binding proteins. The subset of proteins exposed on the bacterial cell surface, and thus interacting with extracellular milieu, constitutes the surfaceome. Here, we review exhaustively the current molecular mechanisms involved in protein attachment within the cell envelope of Gram-positive bacteria, from single protein to macromolecular protein structure.
Subject(s)
Gram-Positive Bacteria/chemistry , Membrane Proteins/chemistry , Amino Acid Sequence , Aminoacyltransferases/physiology , Bacterial Proteins/chemistry , Bacterial Proteins/physiology , Cell Membrane/physiology , Cell Wall/chemistry , Cell Wall/metabolism , Cellulosomes/chemistry , Cellulosomes/physiology , Choline/metabolism , Cysteine Endopeptidases/physiology , Fimbriae, Bacterial/chemistry , Fimbriae, Bacterial/physiology , Flagella/chemistry , Flagella/physiology , Gram-Positive Bacteria/physiology , Gram-Positive Bacteria/ultrastructure , Lipoproteins/chemistry , Lipoproteins/physiology , Membrane Glycoproteins/chemistry , Membrane Glycoproteins/physiology , Membrane Proteins/physiology , Molecular Sequence Data , Mucoproteins/chemistry , Mucoproteins/metabolism , Protein Binding/physiology , Protein Structure, Quaternary/physiologyABSTRACT
Consistent information about protein secretion in Gram-positive bacteria is essentially restricted to the model organism Bacillus subtilis. Among genome-sequenced clostridia, Clostridium acetobutylicum has been the most extensively studied from a physiological point of view and is the organism for which the largest variety of molecular biology tools have been developed. Following in silico analyses, both secreted proteins and protein secretion systems were identified. The Tat (Twin arginine translocation; TC #2.A.64) pathway and ABC (ATP binding cassette) protein exporters (TC #3.A.1.) could not be identified, but the Sec (secretion) pathway (TC #3.A.5) appears to be used prevalently. Similarly, a flagella export apparatus (FEA; TC #3.A.6.), holins (TC #1.E.), and an ESAT-6/WXG100 (early secreted antigen target of 6 kDa/proteins with a WXG motif of approximately 100 residues) secretion system were identified. Here, we report for the first time the identification of a fimbrilin protein exporter (FPE; TC #3.A.14) and a Tad (tight adherence) export apparatus in C. acetobutylicum. This investigation highlights the potential use of this saprophytic bacterium in biotechnological and biomedical applications as well as a model organism for studying protein secretion in pathogenic Gram-positive bacteria.
