Clostridium acetobutylicum grows vegetatively in a biofilm rich in heteropolysaccharides and cytoplasmic proteins

Table 3 Major C. acetobutylicum biofilm proteins that have been reported as non-classically secreted proteins with potential moonlighting functions

Intracellular function	Moonlighting function
Chaperones
Molecular chaperone groel	Adhesin [33, 35,36,37]; bind mucin, invertase and fibronectin [38, 39]
Molecular chaperone dnak	Bind plasminogen and invertase [40,41,42]
Heat shock protein grpe	Not characterized [32, 39, 43]
Molecular chaperone groes	Not characterized [32, 43]
Cold shock protein	Not characterized [44, 45]
Protein synthesis and nucleic acid stability
Elongation factor Tu (Ef-Tu)	Attach to human cells, bind fibronectin and plasminogen [46,47,48,49]
Trigger factor	Not characterized [43, 44, 50, 51]
Ribosomal protein L29	Not characterized [43, 45, 51]
Ribosomal protein S15	Not characterized [52, 53]
Ribosomal protein L7/L12	Not characterized [52, 54]
Central metabolism
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH)	Adhesin [55,56,57]; bind plasminogen, collagen, fibronectin and RNA [34, 58, 59]
Triosephosphate isomerase	Adhesin [33, 60]; bind plasminogen, laminin and fibronectin [61, 62]
Alcohol dehydrogenase	Bind plasminogen [63, 64]
Pyruvate: ferredoxin oxidoreductase	Adhesin [65, 66]
Electron transfer flavoprotein beta-subunit	Not characterized [44, 50, 54]
Acetyl coenzyme A acetyltransferase (thiolase)	Not characterized [44, 67]
Rubrerythrin	Not characterized [52, 68]
Acyl carrier protein, ACP	Not characterized [69, 70]

ISSN: 2731-3654