RESUMO
ent-Kaurene is a biosynthetic intermediate diterpene of phytohormone gibberellins, and is biosynthesized from geranylgeranyl diphosphate via ent-copalyl diphosphate (ent-CDP). The successive cyclization is catalyzed by two distinct diterpene synthases, ent-CDP synthase (ent-CPS) and ent-kaurene synthase (KS). Homologs of these diterpene synthase genes have been reported to be involved in the biosynthesis of specialized-metabolic diterpenoids for defense in several plant species, including rice (Oryza sativa). These diterpene synthases consist of three domains, αßγ domains. Active sites of ent-CPS exist at the interface of ß and γ domain, while those of KS are located within the α domain. We herein carried out domain-deletion experiments using several KSs and KS like enzymes (KSLs) to obtain insights into the roles of domains other than active-site domains. As previously reported in taxadiene synthase, deletion of γ or ßγ domains drastically decreased activities of specialized-metabolic OsKSL5, OsKSL8, OsKSL7 and OsKSL10 in O. sativa. However, unexpectedly, only α domains of several gibberellin-biosynthetic KSs, including OsKS1 in O. sativa, AtKS in Arabidopsis thaliana, TaKS in wheat (Triticum aestivum) and BdKS1 in Brachypodium distachyon, retained their original functions. Additionally, the specialized-metabolic OsKSL4, which is closely related to OsKS1, also functioned without its ßγ domains. Domain-swapping experiments showed that replacing ßγ domains in OsKSL7 with those from other KS/KSLs retained the OsKSL7 activity. Moreover, deletion of ßγ domains of bifunctional PpCPS/KS in moss (Physcomitrella patens) drastically impaired its KS-related activity. Thus, we demonstrate that monofunctional gibberellin-biosynthetic KSs are the unique diterpene synthases that retain their functions without ßγ domains.
Assuntos
Alquil e Aril Transferases , Giberelinas , Oryza , Proteínas de Plantas , Giberelinas/metabolismo , Alquil e Aril Transferases/metabolismo , Alquil e Aril Transferases/genética , Alquil e Aril Transferases/química , Oryza/enzimologia , Oryza/genética , Oryza/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Proteínas de Plantas/química , Domínio Catalítico , Diterpenos do Tipo Caurano/metabolismo , Diterpenos do Tipo Caurano/química , Arabidopsis/genética , Arabidopsis/enzimologia , Arabidopsis/metabolismo , Diterpenos/metabolismo , Diterpenos/química , Domínios Proteicos , CatáliseRESUMO
Background: Kluyvera intermedia is a bacterium indigenous to humans. But Kluyvera intermedia bacteremia has been not reported thus far. We report a case of Kluyvera intermedia bacteremia with septic shock due to left obstructive pyelonephritis as a result of urolithiasis. Case presentation: A 66-year-old woman with septic shock due to left obstructive pyelonephritis was transferred to our hospital. Tazobactam/Piperacillin 4.5 g was administered every 8 h for 5 days. The patient's condition improved, and she was transferred back to the previous hospital. Kluyvera intermedia was obtained by blood cultures. The patient was successfully treated with a two-week course of antibiotics. Conclusions: We describe the first case of bacteremia with septic shock caused by Kluyvera intermedia. Kluyvera intermedia can be a causative pathogen of septic shock. Since this bacterium has not been reported in the past, we expect further reports and the accumulation of cases in the future.
