The PIF1-miR408-PLANTACYANIN Repression Cascade Regulates Light-Dependent Seed Germination

Light-dependent seed germination is a vital process for many seed plants. A decisive event in light-induced germination is degradation of the central repressor PHYTOCHROME INTERACTING FACTOR 1 (PIF1). The balance between gibberellic acid (GA) and abscisic acid (ABA) helps to control germination. However, the cellular mechanisms linking PIF1 turnover to hormonal balancing remain elusive. Here, employing far-red light-induced Arabidopsis thaliana seed germination as the experimental system, we identified PLANTACYANIN (PCY) as an inhibitor of germination. It is a blue copper protein associated with the vacuole that is both highly expressed in mature seeds and rapidly silenced during germination. Molecular analyses showed that PIF1 binds to the miR408 promoter and represses miR408 accumulation. This in turn posttranscriptionally modulates PCY abundance, forming the PIF1-miR408-PCY repression cascade for translating PIF1 turnover to PCY turnover during early germination. Genetic analysis, RNA-sequencing, and hormone quantification revealed that PCY is necessary and sufficient to maintain the PIF1-mediated seed transcriptome and the low-GA-high-ABA state. Furthermore, we found that PCY domain organization and regulation by miR408 are conserved features in seed plants. These results revealed a cellular mechanism whereby PIF1-relayed external light signals are converted through PCY turnover to internal hormonal profiles for controlling seed germination.

A protease-mediated mechanism regulates the cytochrome c6/plastocyanin switch in Synechocystis sp. PCC 6803

After the Great Oxidation Event (GOE), iron availability was greatly decreased, and photosynthetic organisms evolved several alternative proteins and mechanisms. One of these proteins, plastocyanin, is a type I blue-copper protein that can replace cytochrome c6 as a soluble electron carrier between cytochrome b6f and photosystem I. In most cyanobacteria, expression of these two alternative proteins is regulated by copper availability, but the regulatory system remains unknown. Herein, we provide evidence that the regulatory system is composed of a BlaI/CopY-family transcription factor (PetR) and a BlaR-membrane protease (PetP). PetR represses petE (plastocyanin) expression and activates petJ (cytochrome c6), while PetP controls PetR levels in vivo. Using whole-cell extracts, we demonstrated that PetR degradation requires both PetP and copper. Transcriptomic analysis revealed that the PetRP system regulates only four genes (petE, petJ, slr0601, and slr0602), highlighting its specificity. Furthermore, the presence of petE and petRP in early branching cyanobacteria indicates that acquisition of these genes could represent an early adaptation to decreased iron bioavailability following the GOE.

A protease-mediated mechanism regulates the cytochrome c6/ plastocyanin switch in Synechocystis sp. PCC 6803

After the Great Oxidation Event (GOE), iron availability was greatly decreased and photosynthetic organisms evolved several alternative proteins and mechanisms. One of these proteins, plastocyanin, is a type I blue-copper protein that can replace cytochrome c6 as a soluble electron carrier between cytochrome b6f and photosystem I. In most cyanobacteria, expression of these two alternative proteins is regulated by copper availability, but the regulatory system remains unknown. Herein, we provide evidence that the regulatory system is composed of a BlaI/CopY family transcription factor (PetR) and a BlaR membrane protease (PetP). PetR represses petE (plastocyanin) expression and activates petJ (cytochrome c6), while PetP controls PetR levels in vivo. Using whole-cell extracts, we demonstrated that PetR degradation requires both PetP and copper. Transcriptomic analysis revealed that the PetRP system regulates only four genes (petE, petJ, slr0601, and slr0602), highlighting its specificity. Furthermore, the presence of petE and petRP in early branching cyanobacteria indicates that acquisition of these genes could represent an early adaptation to decreased iron bioavailability following the GOE.Significance StatementAfter the appearance of oxygenic photosynthesis, Fe became oxidized and its solubility and availability were greatly decreased. This generated a problem for most organisms since they are strongly dependent on Fe, especially photosynthetic organisms. In response, organisms evolved alternatives to Fe-containing proteins such as plastocyanin, a copper protein that substitutes for cytochrome c6 in photosynthesis. Expression of these two proteins in cyanobacteria is regulated by Cu availability, but the regulatory system remains unknown. Herein, we describe the regulatory system for these alternative proteins in photosynthesis in cyanobacteria. The mechanism involves a transcription factor (PetR) and a membrane protease (PetP) that degrades PetR in the presence of Cu.

OsmiR528 regulates rice-pollen intine formation by targeting an uclacyanin to influence flavonoid metabolism

The intine, the inner layer of the pollen wall, is essential for the normal development and germination of pollen. However, the composition and developmental regulation of the intine in rice (Oryza sativa) remain largely unknown. Here, we identify a microRNA, OsmiR528, which regulates the formation of the pollen intine and thus male fertility in rice. Themir528knockout mutant aborted pollen development at the late binucleate pollen stage, significantly decreasing the seed-setting rate. We further demonstrated that OsmiR528 affects pollen development by directly targeting the uclacyanin geneOsUCL23(encoding a member of the plant-specific blue copper protein family of phytocyanins) and regulating intine deposition.OsUCL23overexpression phenocopied themir528mutant. The OsUCL23 protein localized in the prevacuolar compartments (PVCs) and multivesicular bodies (MVBs). We further revealed that OsUCL23 interacts with a member of the proton-dependent oligopeptide transport (POT) family of transporters to regulate various metabolic components, especially flavonoids. We propose a model in which OsmiR528 regulates pollen intine formation by directly targetingOsUCL23and in which OsUCL23 interacts with the POT protein on the PVCs and MVBs to regulate the production of metabolites during pollen development. The study thus reveals the functions of OsmiR528 and an uclacyanin during pollen development.

POTENSI JAMUR TIRAM PUTIH ( QTRAMETES SP.) KAYA LAKASE UNTUK BIOMODIFIKASI MODEL LIMBAH OBAT INDUSTI FARMASI

Proses sintesis kimia dari industri farmasi menghasilkan air limbah yang memiliki karakter bervariasi. Pembuangan bahan limbah seperti obat yang tidak digunakan lagi, fasilitas untuk produksi farmasi, limbah rumah sakit,ini merupakan sumber polutan. Lakase (EC.1.10.3.2) merupakan enzim oksidoreduktase, termasuk dalam kelompok enzim yang disebut protein tembaga biru (blue copper protein), protein enzim ini mengandung logam tembaga katalitik, yang dapat mengikat oksigen molekuler dan dapat mengoksidasi substrat kaya elektron yang berasal dari fenolik dan non-fenolik dengan air dengan mekanisme reaksi katalis-radikal. Lakase terdapat pada tanaman tingkat tinggi yang sudah lapuk, seperti halnya jamur, bakteri dan serangga, dan kelompok yang paling banyak ditemukan dari enzim hingga saat ini berasal dari jamur, memiliki fungsi lakase yang beragam. Model kimia yang dipilih untuk penelitian ini adalah diklofenak dan ibuprofen, karena merupakan obat yang muncul dengan frekuensi terbanyak dalam analisis air limbah akibat konsumsi yang digunakan sebagai anti-inflamasi dan analgesik. Isolasi parsial enzim lakase menggunakan garam amunium sulfat, aktivitas enzim lakase diuji potensinya sebagai katalis reaksi biodegradasi limbah farmasi. Sampel sebagai bahan aktif secara umum dievaluasi dengan secara eksperimental untuk melihat degradasi biologis sederhana, yaitu menggunakan lakase mentah dari spesies Trametes. Hasil optimal dicapai sebagai enzim mentah dengan cara diendapkan menggunakan aseton dengan kadar 60%; aktivitas spesifik ditemukan menjadi 0,67 (unit / mg), dan menunjukkan dapat dimanfaatkan untuk menangani pengurangan bahan limbah farmasi berbahaya. Biomodifikasi sangat diharapkan untuk dilakukan pada penelitian selanjutnya karena memiliki efek positif yang dapat menurunkan tingkat toksisitas dari obat-obatan yang terdapat sebagai limbah.