The Bacillus subtilis Sfp protein activates the peptidyl carrier protein (PCP) domains of surfactin synthetase by transferring the 4′‐phosphopantetheinyl moiety of coenzyme A (CoA) to a serine residue conserved in all PCPs. Its wide PCP substrate spectrum renders Sfp a biotechnologically valuable enzyme for use in combinatorial non‐ribosomal peptide synthesis. The structure of the Sfp–CoA complex determined at 1.8 Å resolution reveals a novel α/β‐fold exhibiting an unexpected intramolecular 2‐fold pseudosymmetry. This suggests a similar fold and dimerization mode for the homodimeric phosphopantetheinyl transferases such as acyl carrier protein synthase. The active site of Sfp accommodates a magnesium ion, which is complexed by the CoA pyrophosphate, the side chains of three acidic amino acids and one water molecule. CoA is bound in a fashion that differs in many aspects from all known CoA–protein complex structures. The structure reveals regions likely to be involved in the interaction with the PCP substrate.
Protein dynamics plays an important role in protein function. Many functionally important motions occur on the microsecond and low millisecond time scale and can be characterized by nuclear magnetic resonance relaxation experiments. We describe the different states of a peptidyl carrier protein (PCP) that play a crucial role in its function as a peptide shuttle in the nonribosomal peptide synthetases of the tyrocidine A system. Both apo-PCP (without the bound 4′-phosphopantetheine cofactor) and holo-PCP exist in two different stable conformations. We show that one of the apo conformations and one of the holo conformations are identical, whereas the two remaining conformations are only detectable by nuclear magnetic resonance spectroscopy in either the apo or holo form. We further demonstrate that this conformational diversity is an essential prerequisite for the directed movement of the 4′-PP cofactor and its interaction with externally acting proteins such as thioesterases and 4′-PP transferase.
Ginger (Zingiber officinale Rosc.) belongs to the family Zingiberaceae. The health-promoting perspective of ginger is attributed to its rich phytochemistry. This study aimed to review the current evidence on ginger effects as an anti-inflammatory and anti-oxidative. We searched MEDLINE for related publications using “ginger” and “anti-oxidative” and “ginger” and “anti-inflammatory” as keywords. This search had considered Papers that had been published between 2000 and 2010 without any filter. The anticancer potential of ginger is well documented and its functional ingredients like gingerols, shogaol, and paradols are the valuable ingredients which can prevent various cancers. This review concludes to favor ginger but some ambiguities necessitate further research before claiming its efficacy.
The acyl carrier proteins (ACPs) of fatty acid synthase and polyketide synthase as well as peptidyl carrier proteins (PCPs) of nonribosomal peptide synthetases are modified by 4′-phosphopantetheinyl transferases from inactiveapo-enzymes to their active holo forms by transferring the 4′-phosphopantetheinyl moiety of coenzyme A to a conserved serine residue of the carrier protein. 4′-Phosphopantetheinyl transferases have been classified into two types; the AcpS type accepts ACPs of fatty acid synthase and some ACPs of type II polyketide synthase as substrates, whereas the Sfp type exhibits an extraordinarily broad substrate specificity. Based on the previously published co-crystal structure of Bacillus subtilis AcpS and ACP that provided detailed information about the interacting residues of the two proteins, we designed a novel hybrid PCP by replacing the Bacillus brevis TycC3-PCP helix 2 with the corresponding helix of B. subtilis ACP that contains the interacting residues. This was performed for the PCP domain as a single protein as well as for the TycA-PCP domain within the nonribosomal peptide synthetase module TycA from B. brevis. Both resulting proteins, designated hybrid PCP (hPCP) and hybrid TycA (hTycA), were modified in vivo during heterologous expression in Escherichia coli (hPCP, 51%; hTycA, 75%) and in vitro with AcpS as well as Sfp to 100%. The designated hTycA module contains two other domains: an adenylation domain (activating phenylalanine to Phe-AMP and afterward transferring the Phe to the PCP domain) and an epimerization domain (converting the PCP-bound l-Phe to d-Phe). We show here that the modified PCP domain of hTycA communicates with the adenylation domain and that the co-factor of holo-hPCP is loaded with Phe. However, communication between the hybrid PCP and the epimerization domain seems to be disabled. Nevertheless, hTycA is recognized by the next proline-activating elongation module TycB1in vitro, and the dipeptide is formed and released as diketopiperazine.