Regulation pathway | Regulator | Function | Effect on surfactin yield | References |
---|---|---|---|---|
Transcription of the srfAA-AD operon | ComX, ComA-ComP | ComP responds to the extracellular peptide pheromone ComX, then undergoes autophosphorylation and subsequently interacts with ComA to form ComA -P, ComA-P activates transcription of the srfAA-AD | Positive | |
RapC, RapF, RapA4 | Binding with ComA, then inhibits ComA-P and Psrf interaction | Negative | ||
RapD, RapG, RapH, RapK | Overexpression of these Rap proteins inhibits srfAA-AD expression | Negative | ||
Rap60, RapQ | Regulates ComA activity by forming a ternary complex with ComA and DNA and inhibit srfAA-AD expression | Negative | ||
PhrC, PhrF, PhrG, PhrH, PhrK, Phr60, PhrQ, PhrA4 | Inhibits the activity of their cognate Rap proteins | Positive | ||
RsiX, SigX | Disruption of rsiX activates sigX, which increases rapD expression | Negative | [40] | |
RghR | Repress rapD, rapG, and rapH expression | Positive | [35] | |
PhoR-PhoP | Positively regulates surfactin production under low phosphorus conditions | Positive | ||
DegU | DegU directly binds to the srfAA-AD promoter or indirectly regulates srfAA-AD expression by regulating other genes in undomesticated wild strain. Knock out of the degU gene enhances surfactin production | Negative | ||
Spo0A | Global regulator initiates sporulation. Deletion of spo0A enhances surfactin synthesis | Negative | [49] | |
CodY | A global regulator that inhibits srfAA-AD transcription by competing with RNA polymerase binding sites in the srfAA-AD promoter region | Negative | [50] | |
Spx | Spx occupies overlapping sites in the αCTD region of RNA polymerase which inhibits the binding between ComA-P and RNA polymerase with the srfAA-AD promoter | Negative | ||
PerR | Competitively binding to the srfAA-AD promoter region bound by ComA-P | Negative | [53] | |
Branched chain fatty acid synthesis | AccA, AccB, AccC, AccD | Acetyl-CoA carboxylase (ACCase) complex, catalyzes the formation of malonyl-CoA from acetyl-CoA | Positive | [54] |
YngH | ACCase subunit (biotin carboxylase II), could maintain Acetyl-CoA ACCase activity | Positive | [55] | |
FabD | Acyl carrier protein transacylase, converts Malonyl-CoA to malonyl-acyl carrier protein (ACP) | Positive | [56] | |
FabHB | β-ketoacyl-acyl carrier protein synthase III (FabHB) catalyzes the condensation of β-keto acyl-ACP from malonyl-ACP and branched α-ketoacyl CoA | Positive | [56] | |
LcfA, YhfL, YhfT, YngI | Fatty acyl-CoA ligases | Positive | ||
Amino acid synthesis | YrpC, RacE, MurC | Associated with l-Glu consumption | Negative | |
PyrB, PyrC | Participates in the branching pathway for l-Asp biosynthesis, catalyzes the formation of Uracil from l-Asp | Positive | [61] | |
bkdAA, bkdAB, lpdV | Involved in the l-Leu and l-Val metabolic pathways, alters the proportion of surfactin isoforms | Negative | ||
Surfactin secretion and immunity | YcxA, KrsE | Transport membrane proteins, YcxA and KrsE interact with the polar amino acid of surfactin | Positive | |
YerP | Transport membrane protein and homologous to the resistance and cytokinesis family of PMF-dependent efflux pumps | Positive | [23] |