Dissection of Synechococcus rubisco large subunit sections involved in holoenzyme formation in Escherichia coli by combinatorial section swapping and sequence analyses

Engineering the CO2-fixing enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) to improve photosynthesis has long been sought. Rubisco large subunits (RbcL) are highly-conserved but because of certain undefined sequence differences, plant Rubisco research cannot fully utilise the robust heterologous Escherichia coli expression system and its GroEL folding machinery. Previously, a series of chimeric cyanobacteria Synechococcus elongatus Rubisco, incorporated with sequences from the green alga Chlamydomonas reinhardtii, were expressed in E. coli; differences in RbcL sections essential for holoenzyme formation were pinpointed. In this study, the remaining sections, presumably not crucial for holoenzyme formation and also the small subunit (RbcS), are substituted to further ascertain the possible destabilising effects of multiple section mutations. To that end, combinations of Synechococcus RbcL Sections 1 (residues 1-47), 2 (residues 48-97), 5 (residues 198-247) and 10 (residues 448-472), and RbcS, were swapped with collinear Chlamydomonas sections and expressed in E. coli. Interestingly, only the chimera with Sections 1 and 2 together produces holoenzyme and an interaction network of complementing amino acid changes is delineated by crystal structure analysis. Furthermore, sequence-based analysis also highlighted possible GroEL binding site differences between the two RbcLs

Brassinosteroid insensitive 1-associated kinase 1 (OsI-BAK1) is associated with grain filling and leaf development in rice

Brassinosteroid Insensitive 1 (BRI1)-Associated Kinase I (BAK1) has been reported to interact with BRI1 for brassinosteroid (BR) perception and signal transduction that regulate plant growth and development. The aim of this study is to investigate the functions of a rice OsBAK1 homologue, designated as OsI-BAK1, which is highly expressed after heading. Silencing of OsI-BAK1 in rice plants produced a high number of undeveloped green and unfilled grains compared to the untransformed plants. Histological analyses demonstrated that embryos were either absent or retarded in their development in these unfilled rice grains of OsI-BAK1 RNAi plants. Down regulation of OsI-BAK1 caused a reduction in cell number and enlargement in leaf bulliform cells. Furthermore, transgenic rice plants overexpressing OsI-BAK1 were demonstrated to have corrugated and twisted leaves probably due to increased cell number that caused abnormal bulliform cell structure which were enlarged and plugged deep into leaf epidermis. The current findings suggest that OsI-BAK1 may play an important role in the developmental processes of rice grain filling and leaf cell including the bulliform cells

PANC Study (Pancreatitis: A National Cohort Study): national cohort study examining the first 30 days from presentation of acute pancreatitis in the UK

Abstract Background Acute pancreatitis is a common, yet complex, emergency surgical presentation. Multiple guidelines exist and management can vary significantly. The aim of this first UK, multicentre, prospective cohort study was to assess the variation in management of acute pancreatitis to guide resource planning and optimize treatment. Methods All patients aged greater than or equal to 18 years presenting with acute pancreatitis, as per the Atlanta criteria, from March to April 2021 were eligible for inclusion and followed up for 30 days. Anonymized data were uploaded to a secure electronic database in line with local governance approvals. Results A total of 113 hospitals contributed data on 2580 patients, with an equal sex distribution and a mean age of 57 years. The aetiology was gallstones in 50.6 per cent, with idiopathic the next most common (22.4 per cent). In addition to the 7.6 per cent with a diagnosis of chronic pancreatitis, 20.1 per cent of patients had a previous episode of acute pancreatitis. One in 20 patients were classed as having severe pancreatitis, as per the Atlanta criteria. The overall mortality rate was 2.3 per cent at 30 days, but rose to one in three in the severe group. Predictors of death included male sex, increased age, and frailty; previous acute pancreatitis and gallstones as aetiologies were protective. Smoking status and body mass index did not affect death. Conclusion Most patients presenting with acute pancreatitis have a mild, self-limiting disease. Rates of patients with idiopathic pancreatitis are high. Recurrent attacks of pancreatitis are common, but are likely to have reduced risk of death on subsequent admissions. </jats:sec

イネ タイビョウセイ シグナリング ニ オケル Gタンパク OsRac1 ニ ヨル カッセイ サンソ スカベンジャー メタロチオネイン ノ ハツゲン ヨクセイ

http://library.naist.jp/mylimedio/dllimedio/show.cgi?bookid=100041550&oldid=94520博士 (Doctor)バイオサイエンス (Bioscience)博第386号甲第386

Down-Regulation of Metallothionein, a Reactive Oxygen Scavenger, by the Small GTPase OsRac1 in Rice

Metallothioneins are small, ubiquitous Cys-rich proteins known to be involved in reactive oxygen species (ROS) scavenging and metal homeostasis. We found that the expression of a metallothionein gene (OsMT2b) was synergically down-regulated by OsRac1 and rice (Oryza sativa) blast-derived elicitors. Transgenic plants overexpressing OsMT2b showed increased susceptibility to bacterial blight and blast fungus. OsMT2b-overexpressing cells showed reduced elicitor-induced hydrogen peroxide production. In contrast, homozygous OsMT2b::Tos17-inserted mutant and OsMT2b-RNAi-silenced transgenic cells showed significantly higher elicitor-induced hydrogen peroxide production than the wild-type cells. In vitro assay showed that recombinant OsMT2b protein possessed superoxide- and hydroxyl radical-scavenging activities. Taken together, these results showed that OsMT2b is an ROS scavenger and its expression is down-regulated by OsRac1, thus potentiating ROS, which function as signals in resistance response. The results suggest that OsRac1 plays a dual role as an inducer of ROS production and a suppressor of ROS scavenging

Hyperphosphorylation of a Mitochondrial Protein, Prohibitin, Is Induced by Calyculin A in a Rice Lesion-Mimic Mutant cdr1

The rice (Oryza sativa) lesion-mimic mutants, cell death and resistance (cdr), show spontaneous cell death on the entire leaf and exhibited significant resistance to the rice blast fungus. Our previous studies showed that CDR1 and CDR2 genes negatively regulated the phosphorylation steps leading to the activation of NADPH oxidase, which is associated with oxidative burst. To identify novel factors involved in the phosphorylation steps, the phosphorylation level of total proteins was compared between cdr mutants and wild type using two-dimensional gel electrophoresis. Here, we show that the phosphorylation level of four proteins in cdr1 was increased as compared with the wild type after calyculin A treatment. Partial amino acid sequences revealed that one of the four proteins is homologous to prohibitin (PHB), which has been shown to be associated with senescence and cell death and to function as a chaperone in the assembly of mitochondrial respiratory chain complex in yeast and mammals. Analysis of green fluorescent protein fusions indicated that rice PHB (OsPHB1) was targeted to mitochondria as found in yeast and mammals, suggesting a possibility that PHB is involved in defense response and/or programmed cell death through the mitochondrial function