C-Terminal Domain of Bacillus cereus Hemolysin II Is Able to Interact with Erythrocytes

Russian Journal of Bioorganic Chemistry - Hemolysin II (HlyII) is one of the pathogenic factors of Bacillus cereus. With respect to the prototype of β-barrel toxins, the α-toxin of S....     

The Pore-Forming Properties of SsoHel308 Helicase from Saccharolobus solfataricus

The pore-forming activity of SsoHel308 helicase from extreme thermophilic archaea Saccharolobus solfataricus has been demonstrated for the first time. This protein embedded in rabbit erythrocyte membranes may cause erythrocyte hemolysis. It has been shown that this enzyme forms pores in a planar artificial bilayer membrane and acts as a transformer. After embedding this enzyme into biolayer lipid membranes, the membrane conductivity is altered. Taken together, our results show that SsoHel308 helicase is able to form pores in artificial bilayer membranes and, in some cases, the current that flows across the membranes shares features typical of ion channels. The short lifetime of the pores in the membrane significantly reduces the toxicity of helicase for a living cell. The possibility of directed translocation of single-stranded DNA in the presence of ATP will enable the use of this enzyme as a molecular syringe for injecting single-stranded DNA into living cells.

     

Bacillus cereus can attack the cell membranes of the alga Chara corallina by means of HlyII

We studied the influence of Bacillus cereus bacteria on cells of the freshwater alga Chara corallina. These bacteria and recombinant Bacillus subtilis strains are capable of producing the secreted toxin HlyII, which changes the electrophysiological parameters of the algal electrically excitable plasma membrane by forming pores. Cooperative incubation of bacterial cells, which carry active hlyII gene, and Chara corallina cells caused a decrease in the resting potential (V(m)) and plasma membrane resistance (R(m)) of algal cells. The efficiency of each strain was commensurable with its ability to produce HlyII. Purified hemolysin II caused a similar effect on V(m) and R(m) of intact and perfused cells. This protein changed the kinetics and magnitude of transient voltage-dependent calcium and calcium-activated chloride currents owing to the formation of additional Ca(2+)-permeable pores in algal cell membrane. Occurrence of the cellulose cell wall with pores 2.1 to 4.6nm in diameter suggests that HlyII molecules reach the plasma membrane surface strictly as monomers.     

Pore-forming proteins and adaptation of living organisms to environmental conditions

Pore-forming proteins are powerful “tools” for adaptation of living organisms to environmental conditions. A wide range of these proteins isolated from various sources, from viruses to mammals, has been used for the analysis of their role in the processes of intra- and inter-species competition, defense, attack, and signaling. Here we review a large number of pore-forming proteins from the perspective of their functions, structures, and mechanisms of membrane penetration. Various mechanisms of cell damage, executed by these proteins in the course of formation of a pore and after its passing to conducting state, have been considered: endo- and exocytosis, lysis, necrosis, apoptosis, etc. The role of pore-forming proteins in evolution is discussed. The relevance of practical application of pore formers has been shown, including application in nanotechnological constructions.     

Recombinant xylanase from Streptomyces coelicolor Ac-738: characterization and the effect on xylan-containing products

A xylanase gene was isolated from the genomic DNA of Streptomyces coelicolor Ac-738. The 723-bp full-length gene encoded a 241-amino acid peptide consisting of a 49-residue putative TAT signal peptide and a glycoside hydrolase family-11 domain. The mature enzyme called XSC738 was expressed in Escherichia coli M15[pREP4]. The electrophoretically homogeneous protein with a specific activity of 167 U/mg for beechwood xylan was purified. The pH optimum of XSC738 was at pH 6; a high activity was retained within a pH range of 4.5–8.5. The enzyme was thermostable at 50–60 °C and retained an activity at pH 3.0–7.0. Xylanase XSC738 was activated by Mn²⁺, Co²⁺ and largely inhibited by Cd²⁺, SDS and EDTA. The products of xylan hydrolysis were mainly xylobiose, xylotriose, xylopentaose and xylohexose. Xylotetraose appeared as a minor product. Processing of such agricultural xylan-containing products as wheat, oats, soy flour and wheat bran by xylanase resulted in an increased content of sugars.     

Monoclonal Antibody HlyIIC‑15 to C-End Domain HlyII B. cereus Interacts with the Trombin Recognition Site

Russian Journal of Bioorganic Chemistry - Among the panel of monoclonal antibodies to the recombinant protein HlyIICTD Bacillus cereus an antibody was found capable of forming an immune complex...