spore-adsorption-as-nonrecombinant-display-system-for-enzymes

Spore Adsorption as a Nonrecombinant Display System for Enzymes and Antigens

The bacterial spore is a metabolically quiescent cell, formed by a series of protective layers surrounding a dehydrated cytoplasm. This peculiar structure ...

University of Naples "Federico II"

The ability to produce an extracellular matrix and form multicellular communities is an adaptive behavior shared by many bacteria. In Bacillus subtilis, the model system for spore-forming bacteria, matrix production is one of the possible differentiation pathways that a cell can follow when vegetative growth is no longer feasible. While in B. subtilis the genetic system controlling matrix production has been studied in detail, it is still unclear whether other spore formers utilize similar mechanisms. We report that SF214, a pigmented strain of Bacillus pumilus isolated from the marine environment, can produce an extracellular matrix relying on orthologs of many of the genes known to be important for matrix synthesis in B. subtilis. We also report a characterization of the carbohydrates forming the extracellular matrix of strain SF214. The isolation and characterization of mutants altered in matrix synthesis, pigmentation, and spore formation suggest that in strain SF214 the three processes are strictly interconnected and regulated by a common molecular mechanism. 

Matrix Production, Pigment Synthesis, and Sporulation in a Marine Isolated Strain of Bacillus pumilus.

CotG is an abundant protein initially identified as an outer component of the Bacillus subtilis spore coat. It has an unusual structure characterized by several repeats of positively charged amino acids that are probably the outcome of multiple rounds of gene elongation events in an ancestral minigene. CotG is not highly conserved, and its orthologues are present in only two Bacillus and two Geobacillus species. In B. subtilis, CotG is the target of extensive phosphorylation by a still unidentified enzyme and has a role in the assembly of some outer coat proteins. We report now that most spore-forming bacilli contain a protein not homologous to CotG of B. subtilis but sharing a central "modular" region defined by a pronounced positive charge and randomly coiled tandem repeats. Conservation of the structural features in most spore-forming bacilli suggests a relevant role for the CotG-like protein family in the structure and function of the bacterial endospore. To expand our knowledge on the role of CotG, we dissected the B. subtilis protein by constructing deletion mutants that express specific regions of the protein and observed that they have different roles in the assembly of other coat proteins and in spore germination.

CotG-Like Modular Proteins Are Common among Spore-Forming Bacilli.

Producing antimicrobials is a common adaptive behavior shared by many microorganisms, including marine bacteria. We report that SF214, a marine-isolated strain of , produces at least two different molecules with antibacterial activity: a molecule smaller than 3 kDa active against  and a molecule larger than 10 kDa active against  We focused our attention on the anti- molecule and found that it was active at a wide range of pH conditions and that its secretion was dependent on the growth phase, medium, and temperature. A mass spectrometry analysis of the size-fractionated supernatant of SF214 identified the small anti- molecule as a pumilacidin, a nonribosomally synthesized biosurfactant composed of a mixture of cyclic heptapeptides linked to fatty acids of variable length. The analysis of the SF214 genome revealed the presence of a gene cluster similar to the  locus encoding the multimodular, nonribosomal peptide synthases found in other surfactant-producing bacilli. However, the  cluster of SF214 differed from that present in other surfactant-producing strains of  by the presence of an insertion element previously found only in strains of .

Article	Year
Matrix Production, Pigment Synthesis, and Sporulation in a Marine Isolated Strain of Bacillus pumilus. Marine drugs\| PubMed ID: 26506360	2015
CotG-Like Modular Proteins Are Common among Spore-Forming Bacilli. Journal of bacteriology\| PubMed ID: 26953338	2016
A Marine Isolate of Secretes a Pumilacidin Active against . Marine drugs\| PubMed ID: 29882934	2018

Loredana Baccigalupi

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