Semi-microbiological synthesis of an active lysinoalanine-bridged analog of glucagon-like-peptide-1

Some modified glucagon-like-peptide-1 (GLP-1) analogs are highly important for treating type 2 diabetes. Here we investigated whether GLP-1 analogs expressed in Lactococcus lactis could be substrates for modification and export by the nisin dehydratase and transporter enzyme. Subsequently we introduced a lysinoalanine by coupling a formed dehydroalanine with a lysine and investigated the structure and activity of the formed lysinoalanine-bridged GLP-1 analog. Our data show: (i) GLP-1 fused to the nisin leader peptide is very well exported via the nisin transporter NisT, (ii) production of leader-GLP-1 via NisT is higher than via the SEC system, (iii) leader-GLP-1 exported via NisT was more efficiently dehydrated by the nisin dehydratase NisB than when exported via the SEC system, (iv) individual serines and threonines in GLP-1 are dehydrated by NisB to a significantly different extent, (v) an introduced Ser30 is well dehydrated and can be coupled to Lys34 to form a lysinoalanine-bridged GLP-1 analog, (vi) a lysinoalanine(30-34) variant's conformation shifts in the presence of 25% trifluoroethanol towards a higher alpha helix content than observed for wild type GLP-1 under identical condition, (vii) a lysinoalanine(30-34) GLP-1 variant has retained significant activity. Taken together the data extend knowledge on the substrate specificities of NisT and NisB and their combined activity relative to export via the Sec system, and demonstrate that introducing a lysinoalanine bridge is an option for modifying therapeutic peptides.     

羊毛硫肽的高通量工程改造方法新进展

羊毛硫肽(lanthipeptide)是由核糖体合成并经翻译后修饰产生的肽类天然产物,具有丰富的分子结构和多样的生物活性.新型羊毛硫肽是活性药物的重要来源,可以通过基因组挖掘和工程改造获得.羊毛硫肽前体肽由基因编码,同时其合成酶具有较高的底物杂泛性.基于这些特征,可以对羊毛硫肽的生物合成过程开展高通量工程改造,从而快速...     

Dissecting the catalytic and substrate binding activity of a class II lanthipeptide synthetase BovM

LanM proteins are the synthetases of the class II lanthipeptides, which are responsible for lanthionine or methyllanthionine formation in lanthipeptides. LanMs are bifunctional enzymes with N-terminal dehydratase and C-terminal cyclase domains. However, the catalytic and especially the substrate binding function of LanM are not fully investigated. In this study, we analyzed the function of conserved residues of BovM, which is the synthetase of lanthipeptide bovicin HJ50, with alanine substitution method. Mass spectrometry (MS) and surface plasmon resonance (SPR) analyses showed six hydrophilic residues (e.g. Asp247) were involved in the dehydration activity of BovM and four hydrophobic residues (e.g. Ile254) were responsible for the substrate binding of BovM. In addition, a conserved Asp155 was proposed to be general base in the elimination of phosphates during the dehydration reactions. This research of BovM shed a light on the catalytic and substrate binding mechanism of LanM proteins.