Beta-lactamase-like protein; part of the gene cluster that mediates the biosynthesis of strobilurin A, an antifungal polyketide that contains a key beta-methoxyacrylate toxophore that targets the complex III of the mitochondrial electron transport chain (PubMed:30258052). Strobilurin biosynthesis begins with construction of benzoyl CoA by step-wise elimination of ammonia from phenylalanine by the phenylalanine ammonia-lyase str11, oxygenation by str8 and retro-Claisen reaction to form benzoic acid, which is activated to its CoA thiolester benzoyl CoA by the dedicated CoA ligase str10 (PubMed:30258052). Benzoyl CoA forms the starter unit for the highly reducing polyketide synthase stpks1 that produces the polyketide prestrobilutin A (PubMed:30258052). The FAD-dependent oxygenase str9 then catalyzes the key oxidative rearrangement responsible for the creation of the beta-methoxyacrylate toxophore (PubMed:30258052). Str9 performs epoxidation of the 2,3 olefin of prestrobilutin A, followed by Meinwald rearrangement to furnish the aldehyde intermediate (Probable). Rapid enolization of the aldehyde intermediate would give the beta-methoxyacrylate skeleton and methylations catalyzed by str2 and str3 complete the synthesis and lead to the peroduction of strobilurin A (Probable). The short-chain dehydrogenase stl2 and the dehydrogenase str4 play a role in the shunt pathway leading to the production of bolineol (PubMed:30258052). The cluster encodes no obvious halogenase gene that could be involved in production of strobilurin B, nor any obvious dimethylallyl-transferase that could be involved in the production of strobilurin G (Probable). It is possible that unknown proteins encoded in, or near, the cluster (such as str1 or stl1) may form new classes of halogenases or dimethylally-transferases, or that the responsible genes are located elsewhere on the genome (Probable). Similarly, proteins encoded by str5/str6 hydrolases appear to have no chemical role in the biosynthesis of strobilurin A (Probable). Finally, no obvious self-resistance gene is found within the cluster (Probable). Mycotoxin biosynthesis. The structure of strobilurin A was used for the development of the major class of beta-methoxyacrylate agricultural fungicides since its beta-methoxyacrylate toxophore targets the Qo site of complex III of the mitochondrial electron transport chain and prevents adenosine triphosphate synthesis (PubMed:563391, PubMed:6271595). Compounds such as azoxystrobin (Syngenta) and Kresoxim methyl (BASF) are among the most widely used fungicides worldwide (PubMed:29711574, PubMed:12146165). This class of antifungals are used as effective treatments against a broad range of destructive fungal plant pathogens and make significant contributions to food security (PubMed:29711574, PubMed:12146165). The strobilurin fungicides are estimated to have been worth 3.4 billion dollars in 2015 and they make up 25% of the fungicide market and 6.7% of the total crop protection market (PubMed:30258052). Belongs to the beta-lactamase family. Str5 and str6 form two genes in S.tenacellus whereas they are fused in close related species.