Values of macular ganglion cell-inner plexiform layer and 10-2 visual field measurements in detecting and evaluating glaucoma.

AIM: To assess the performance of macular ganglion cell-inner plexiform layer thickness (mGCIPLT) and 10-2 visual field (VF) parameters in detecting early glaucoma and evaluating the severity of advanced glaucoma. METHODS: Totally 127 eyes from 89 participants (36 eyes of 19 healthy participants, 45 eyes of 31 early glaucoma patients and 46 eyes of 39 advanced glaucoma patients) were included. The relationships between the optical coherence tomography (OCT)-derived parameters and VF sensitivity were determined. Patients with early glaucoma were divided into eyes with or without central 10° of the VF damages (CVFDs), and the diagnostic performances of OCT-derived parameters were assessed. RESULTS: In early glaucoma, the mGCIPLT was significantly correlated with 10-2 VF pattern standard deviation (PSD; with average mGCIPLT: ß=-0.046, 95%CI, -0.067 to -0.024, P<0.001). In advanced glaucoma, the mGCIPLT was related to the 24-2 VF mean deviation (MD; with average mGCIPLT: ß=0.397, 95%CI, 0.199 to 0.595, P<0.001), 10-2 VF MD (with average mGCIPLT: ß=0.762, 95%CI, 0.485 to 1.038, P<0.001) and 24-2 VF PSD (with average mGCIPLT: ß=0.244, 95%CI, 0.124 to 0.364, P<0.001). Except for the minimum and superotemporal mGCIPLT, the decrease of mGCIPLT in early glaucomatous eyes with CVFDs was more severe than that of early glaucomatous eyes without CVFDs. The area under the curve (AUC) of the average mGCIPLT (AUC=0.949, 95%CI, 0.868 to 0.982) was greater than that of the average circumpapillary retinal nerve fiber layer thickness (cpRNFLT; AUC=0.827, 95%CI, 0.674 to 0.918) and rim area (AUC=0.799, 95%CI, 0.610 to 0.907) in early glaucomatous eyes with CVFDs versus normal eyes. CONCLUSION: The 10-2 VF and mGCIPLT parameters are complementary to 24-2 VF, cpRNFLT and ONH parameters, especially in detecting early glaucoma with CVFDs and evaluating the severity of advanced glaucoma in group level.

A pedigree with retinitis pigmentosa and its concomitant ophthalmic diseases.

AIM: To characterize the ophthalmic clinical phenotype of a family with retinitis pigmentosa (RP) and closed-angle glaucoma and to detect pathogenic genes and mutation sites causing RP in this family. METHODS: Ophthalmic clinic performance was examined in detail in 8 enrolled family members. Genomic DNA was extracted from the peripheral blood of 4 family members for whole-exome sequencing (WES) to select potential genetic mutations whose structures were identified by bioinformatics analysis. Then, Sanger sequencing was used in 12 family members and control group members to validate and confirm the disease-causing mutation loci, and we analyzed the genotype-phenotype relationships. RESULTS: The known c.512C>T (p.P171L) mutation in the rhodopsin (RHO) gene was only found in afflicted family members and was confirmed by WES and Sanger sequencing as the pathogenic mutation in this family. In addition to being diagnosed with RP, family member III:4 was found to have bilateral closed-angle glaucoma, high myopia, and concurrent cataracts, and family members II:2 and II:4 had pathological changes of anterior chamber angle narrowing. Family members IV:3 and IV:4 were found to have retinoschisis. CONCLUSION: Glaucoma and related pathological changes, such as retinoschisis, in family members are preliminarily considered RP complications caused by RHO mutation.

FkbN and Tcs7 are pathway-specific regulators of the FK506 biosynthetic gene cluster in Streptomyces tsukubaensis L19.

FK506 (tacrolimus), which is produced by many Streptomyces strains, is clinically used as an immunosuppressive agent and for treatment of inflammatory skin diseases. Here, we identified that the FK506 biosynthetic gene cluster in an industrial FK506-producing strain Streptomyces tsukubaensis L19 is organized as eight transcription units. Two pathway-specific regulators, FkbN and Tcs7, involved in FK506 biosynthesis from S. tsukubaensis L19 were characterized in vivo and in vitro. FkbN activates the transcription of six transcription units in FK506 biosynthetic gene cluster, and Tcs7 activates the transcription of fkbN. In addition, the DNA-binding specificity of FkbN was determined. Finally, a high FK506-producing strain was constructed by overexpression of both fkbN and tcs7 in S. tsukubaensis L19, which improved FK506 production by 89 % compared to the parental strain.

Functions of Type II Thioesterases in Bacterial Polyketide Biosynthesis.

Many polyketides show biological activities and have thus been applied in clinics, as food additives, and in agriculture. Type II thioesterases (TEIIs) play an important role in polyketide biosynthesis. Most TEIIs belong to α/ß-hydrolase family and usually contain a catalytic triad Ser-His-Asp. In polyketide biosynthesis, TEIIs can play an editing role by removal of aberrant non-extendable acyl units in elongation steps, a starter unit selection role by removal of unfavored starter acyl units in initiation steps, and a releasing role by removal of final product in termination steps. Complementation of TEIIs has been observed and applied.

Characterization of Discrete Phosphopantetheinyl Transferases in Streptomyces tsukubaensis L19 Unveils a Complicate Phosphopantetheinylation Network.

Phosphopantetheinyl transferases (PPTases) play essential roles in both primary metabolisms and secondary metabolisms via post-translational modification of acyl carrier proteins (ACPs) and peptidyl carrier proteins (PCPs). In this study, an industrial FK506 producing strain Streptomyces tsukubaensis L19, together with Streptomyces avermitilis, was identified to contain the highest number (five) of discrete PPTases known among any species thus far examined. Characterization of the five PPTases in S. tsukubaensis L19 unveiled that stw ACP, an ACP in a type II PKS, was phosphopantetheinylated by three PPTases FKPPT1, FKPPT3, and FKACPS; sts FAS ACP, the ACP in fatty acid synthase (FAS), was phosphopantetheinylated by three PPTases FKPPT2, FKPPT3, and FKACPS; TcsA-ACP, an ACP involved in FK506 biosynthesis, was phosphopantetheinylated by two PPTases FKPPT3 and FKACPS; FkbP-PCP, an PCP involved in FK506 biosynthesis, was phosphopantetheinylated by all of these five PPTases FKPPT1-4 and FKACPS. Our results here indicate that the functions of these PPTases complement each other for ACPs/PCPs substrates, suggesting a complicate phosphopantetheinylation network in S. tsukubaensis L19. Engineering of these PPTases in S. tsukubaensis L19 resulted in a mutant strain that can improve FK506 production.

The substrate promiscuity of a phosphopantetheinyl transferase SchPPT for coenzyme A derivatives and acyl carrier proteins.

Phosphopantetheinyl transferases (PPTases) catalyze the posttranslational modification of acyl carrier proteins (ACPs) in fatty acid synthases (FASs), ACPs in polyketide synthases, and peptidyl carrier proteins (PCPs) in nonribosomal peptide synthetases (NRPSs) in all organisms. Some bacterial PPTases have broad substrate specificities for ACPs/PCPs and/or coenzyme A (CoA)/CoA analogs, facilitating their application in metabolite production in hosts and/or labeling of ACPs/PCPs, respectively. Here, a group II PPTase SchPPT from Streptomyces chattanoogensis L10 was characterized to accept a heterologous ACP and acetyl-CoA. Thus, SchPPT is a promiscuous PPTase and may be used on polyketide production in heterologous bacterial host and labeling of ACPs.

An acyltransferase domain of FK506 polyketide synthase recognizing both an acyl carrier protein and coenzyme A as acyl donors to transfer allylmalonyl and ethylmalonyl units.

UNLABELLED: Acyltransferase (AT) domains of polyketide synthases (PKSs) usually use coenzyme A (CoA) as an acyl donor to transfer common acyl units to acyl carrier protein (ACP) domains, initiating incorporation of acyl units into polyketides. Two clinical immunosuppressive agents, FK506 and FK520, are biosynthesized by the same PKSs in several Streptomyces strains. In this study, characterization of AT4FkbB (the AT domain of the fourth module of FK506 PKS) in transacylation reactions showed that AT4FkbB recognizes both an ACP domain (ACPT csA) and CoA as acyl donors for transfer of a unique allylmalonyl (AM) unit to an acyl acceptor ACP domain (ACP4FkbB), resulting in FK506 production. In addition, AT4FkbB uses CoA as an acyl donor to transfer an unusual ethylmalonyl (EM) unit to ACP4FkbB, resulting in FK520 production, and transfers AM units to non-native ACP acceptors. Characterization of AT4FkbB in self-acylation reactions suggests that AT4FkbB controls acyl unit specificity in transacylation reactions but not in self-acylation reactions. Generally, AT domains of PKSs only recognize one acyl donor; however, we report here that AT4FkbB recognizes two acyl donors for the transfer of different acyl units. DATABASE: Nucleotide sequence data have been submitted to the GenBank database under accession numbers KJ000382 and KJ000383.