## 3 Results and Discussion
### Analysis of Plasmid Presence and Antibiotic Resistance Genes
#### 3.6.2 Thiopeptide and LAP Gene Clusters  
BGC Region 2 Derived from _Lentzea_ sp. JNUCC 0626  
The antiSMASH-based genomic analysis of _Lentzea_ sp. JNUCC 0626 identified genes in BGC region 2 that are homologous to those responsible for lactazole biosynthesis, a potent antibiotic thiopeptide primarily synthesized by _Streptomyces lactacystinaes_. Within this region, homologs of key biosynthetic genes (_lazA-lazF_) were found that are responsible for precursor synthesis, azole ring formation, and maturation [48]. Specifically, the _lazA_ gene encodes the precursor peptide, which undergoes post-translational modifications to yield the active thiopeptide. The genes _lazB_, _lazC_, _lazD_, and _lazE_ are involved in modifying the precursor peptide, facilitating the formation of azole rings and other structural elements essential for lactazole activity. The _lazF_ gene likely participates in further modifications, potentially contributing to cyclization or other maturation processes necessary for the production of the final bioactive compound. The comparative analysis of the lactazole biosynthetic gene clusters in JNUCC 0626 and _S. lactacystinaes_--as depicted in Figure S5 and detailed in Table S12--demonstrates a conserved operon-like structure across both species. This structural similarity suggests a shared evolutionary pathway for lactazole biosynthesis. A significant finding from this comparative analysis is the sequence variation in the precursor peptide encoded by the _lazA_ gene. In _S. lactacystinaes_, the precursor peptide sequence is \"MSDTIASRVESLDLDQLDLSELTVTSLRDTVALPENGASWGSCSCQASSSCAQQPQDM\", whereas in JNUCC 0626, it is \"MKDLSFDPDDLELGLDAVTSLRDSVALPESGASGGASSCSCGSSSCSTQPQLPAQNA\". These sequence variations may impact the final structure and bioactivity of the lactazole compounds produced by each species. These findings underscore both the genetic and functional homology between JNUCC 0626 and _S. lactacystinaes_, suggesting that while both organisms retain the core machinery for lactazole biosynthesis, they may produce distinct yet related thiopeptides due to minor modifications. Such comparative genomic studies are essential for understanding the diversity in natural product biosynthesis and may offer valuable insights into novel antibiotic discovery.  
BGC Region 31 Derived from _Lentzea_ sp. JNUCC 0626  
The bacteriocin biosynthetic gene cluster (BGC) found in region 31 of _Lentzea_ sp. JNUCC 0626 exhibits similarities to other well-characterized BGCs, such as those responsible for the production of the DNA gyrase inhibitor microcin B17 (GenBank: FM877811), the exotoxin streptolysin (GenBank: AF465842), and the pore-forming toxin listeriolysin (GenBank: AE017262). These clusters typically encode precursor peptides (e.g., SagA) alongside enzymes such as SagB/ThOx family dehydrogenases (e.g., SagB), cyclodehydratasees (e.g., SagC), and YcaO-like proteins (e.g., SagD). As depicted in Figure S6 and Table S13, the BGC from JNUCC 0626 region 31 contains proteins with a low sequence identity to these known bacteriocin-related proteins yet retains predicted functional similarities. Specifically, the BLASTP, SWISS-MODEL, and HHPred analyses suggest that proteins XJ1J3287, XJ1J3290, and XJ1J3288 have analogous functions to SagB (19.20%), SagC (22.96%), and SagD (24.45%), respectively.  
Protein XJJ13285 was predicted to be a short peptide composed of 78 amino acids. In contrast, protein XJJ13291 was identified as a MerR family transcriptional regulator. Structural and sequence analyses of protein XJ13292, conducted using AlphaFold, HH-Pred, and SWISS-MODEL, revealed a 69% sequence identity and 82% positive alignment (131 out of 160 residues) with the _Mycobacterium tuberculosis_ amino acid acetyltransferase (PDB: 5 YGE) [49]. Interestingly, unlike many bacteriocin BGCs, no genes encoding peptidases or transporter proteins were found in this region of the _Lentzea_ sp. JNUCC 0626 genome, indicating a potentially unique mechanism of bacteriocin biosynthesis and secretion.