scholarly journals Succinate:Quinol Oxidoreductases in the Cyanobacterium Synechocystis sp. Strain PCC 6803: Presence and Function in Metabolism and Electron Transport

2000 ◽  
Vol 182 (3) ◽  
pp. 714-722 ◽  
Author(s):  
Jason W. Cooley ◽  
Crispin A. Howitt ◽  
Wim F. J. Vermaas
Keyword(s):  
Succinate Dehydrogenase ◽  
Dehydrogenase Activity ◽  
Double Mutant ◽  
Sequence Similarity ◽  
Open Reading Frames ◽  
Growth Media ◽  
Wild Type ◽  
Succinate Dehydrogenase Activity ◽  
Reading Frames ◽  
Pcc 6803

ABSTRACT The open reading frames sll1625 andsll0823, which have significant sequence similarity to genes coding for the FeS subunits of succinate dehydrogenase and fumarate reductase, were deleted singly and in combination in the cyanobacterium Synechocystis sp. strain PCC 6803. When the organic acid content in the Δsll1625 and Δsll0823 strains was analyzed, a 100-fold decrease in succinate and fumarate concentrations was observed relative to the wild type. A similar analysis for the Δsll1625 Δsll0823 strain revealed that 17% of the wild-type succinate levels remained, while only 1 to 2% of the wild-type fumarate levels were present. Addition of 2-oxoglutarate to the growth media of the double mutant strain prior to analysis of organic acids in cells caused succinate to accumulate. This indicates that succinate dehydrogenase activity had been blocked by the deletions and that 2-oxoglutarate can be converted to succinate in vivo in this organism, even though a traditional 2-oxoglutarate dehydrogenase is lacking. In addition, reduction of the thylakoid plastoquinone pool in darkness in the presence of KCN was up to fivefold slower in the mutants than in the wild type. Moreover, in vitro succinate dehydrogenase activity observed in wild-type membranes is absent from those isolated from the double mutant and reduced in those from the single mutants, further indicating that the sll1625 and sll0823 open reading frames encode subunits of succinate dehydrogenase complexes that are active in the thylakoid membrane of the cyanobacterium.

scholarly journals Type 2 NADH Dehydrogenases in the CyanobacteriumSynechocystis sp. Strain PCC 6803 Are Involved in Regulation Rather Than Respiration

1999 ◽  
Vol 181 (13) ◽  
pp. 3994-4003 ◽  
Author(s):  
Crispin A. Howitt ◽  
Pacer K. Udall ◽  
Wim F. J. Vermaas
Keyword(s):  
Sequence Similarity ◽  
Open Reading Frames ◽  
Wild Type ◽  
Ps Ii ◽  
Transfer Rates ◽  
Plastoquinone Pool ◽  
Ps I ◽  
Reading Frames ◽  
Pcc 6803

ABSTRACT Analysis of the genome of Synechocystis sp. strain PCC 6803 reveals three open reading frames (slr0851,slr1743, and sll1484) that may code for type 2 NAD(P)H dehydrogenases (NDH-2). The sequence similarity between the translated open reading frames and NDH-2s from other organisms is low, generally not exceeding 30% identity. However, NAD(P)H and flavin adenine dinucleotide binding motifs are conserved in all three putative NDH-2s in Synechocystis sp. strain PCC 6803. The three open reading frames were cloned, and deletion constructs were made for each. An expression construct containing one of the three open reading frames, slr1743, was able to functionally complement anEscherichia coli mutant lacking both NDH-1s and NDH-2s. Therefore, slr0851, slr1743, andsll1484 have been designated ndbA,ndbB, and ndbC, respectively. Strains that lacked one or more of the ndb genes were created in wild-type and photosystem (PS) I-less backgrounds. Deletion ofndb genes led to small changes in photoautotrophic growth rates and respiratory activities. Electron transfer rates into the plastoquinone pool in thylakoids in darkness were consistent with the presence of a small amount of NDH-2 activity in thylakoids. No difference was observed between wild-type and the Ndb-less strains in the banding patterns seen on native gels when stained for either NADH or NADPH dehydrogenase activity, indicating that the Ndb proteins do not accumulate to high levels. A striking phenotype of the PS I-less background strains lacking one or more of the NDH-2s is that they were able to grow at high light intensities that were lethal to the control strain but they retained normal PS II activity. We suggest that the Ndb proteins in Synechocystis sp. strain PCC 6803 are redox sensors and that they play a regulatory role responding to the redox state of the plastoquinone pool.

scholarly journals Genetic Investigation of the Catabolic Pathway for Degradation of Abietane Diterpenoids by Pseudomonas abietaniphilaBKME-9

2000 ◽  
Vol 182 (13) ◽  
pp. 3784-3793 ◽  
Author(s):  
Vincent J. J. Martin ◽  
William W. Mohn
Keyword(s):  
Gene Cluster ◽  
Sequence Similarity ◽  
Open Reading Frames ◽  
Ring Cleavage ◽  
Catabolic Pathway ◽  
Transcriptional Fusion ◽  
Abietane Diterpenoids ◽  
Genes Encoding ◽  
Dna Fragment ◽  
Reading Frames

ABSTRACT We have cloned and sequenced the dit gene cluster encoding enzymes of the catabolic pathway for abietane diterpenoid degradation by Pseudomonas abietaniphila BKME-9. Thedit gene cluster is located on a 16.7-kb DNA fragment containing 13 complete open reading frames (ORFs) and 1 partial ORF. The genes ditA1A2A3 encode the α and β subunits and the ferredoxin of the dioxygenase which hydroxylates 7-oxodehydroabietic acid to 7-oxo-11,12-dihydroxy-8,13-abietadien acid. The dioxygenase mutant strain BKME-941 (ditA1::Tn5) did not grow on nonaromatic abietanes, and transformed palustric and abietic acids to 7-oxodehydroabietic acid in cell suspension assays. Thus, nonaromatic abietanes are aromatized prior to further degradation. Catechol 2,3-dioxygenase activity of xylEtranscriptional fusion strains showed induction of ditA1and ditA3 by abietic, dehydroabietic, and 7-oxodehydroabietic acids, which support the growth of strain BKME-9, as well as by isopimaric and 12,14-dichlorodehydroabietic acids, which are diterpenoids that do not support the growth of strain BKME-9. In addition to the aromatic-ring-hydroxylating dioxygenase genes, thedit cluster includes ditC, encoding an extradiol ring cleavage dioxygenase, and ditR, encoding an IclR-type transcriptional regulator. Although ditR is not strictly required for the growth of strain BKME-9 on abietanes, aditR::Kmr mutation in aditA3::xylE reporter strain demonstrated that it encodes an inducer-dependent transcriptional activator of ditA3. An ORF with sequence similarity to genes encoding permeases (ditE) is linked with genes involved in abietane degradation.

scholarly journals Two Unrelated 8-Vinyl Reductases Ensure Production of Mature Chlorophylls in Acaryochloris marina

2016 ◽  
Vol 198 (9) ◽  
pp. 1393-1400 ◽  
Author(s):  
Guangyu E. Chen ◽  
Andrew Hitchcock ◽  
Philip J. Jackson ◽  
Roy R. Chaudhuri ◽  
Mark J. Dickman ◽  
...  
Keyword(s):  
Transcriptional Control ◽  
Sequence Similarity ◽  
Open Reading Frames ◽  
High Sequence Similarity ◽  
Content Type ◽  
Ethyl Group ◽  
Acaryochloris Marina ◽  
Vinyl Group ◽  
Vinyl Reductase ◽  
Reading Frames

ABSTRACTThe major photopigment of the cyanobacteriumAcaryochloris marinais chlorophylld, while its direct biosynthetic precursor, chlorophylla, is also present in the cell. These pigments, along with the majority of chlorophylls utilized by oxygenic phototrophs, carry an ethyl group at the C-8 position of the molecule, having undergone reduction of a vinyl group during biosynthesis. Two unrelated classes of 8-vinyl reductase involved in the biosynthesis of chlorophylls are known to exist, BciA and BciB. The genome ofAcaryochloris marinacontains open reading frames (ORFs) encoding proteins displaying high sequence similarity to BciA or BciB, although they are annotated as genes involved in transcriptional control (nmrA) and methanogenesis (frhB), respectively. These genes were introduced into an 8-vinyl chlorophylla-producing ΔbciBstrain ofSynechocystissp. strain PCC 6803, and both were shown to restore synthesis of the pigment with an ethyl group at C-8, demonstrating their activities as 8-vinyl reductases. We propose thatnmrAandfrhBbe reassigned asbciAandbciB, respectively; transcript and proteomic analysis ofAcaryochloris marinareveal that bothbciAandbciBare expressed and their encoded proteins are present in the cell, possibly in order to ensure that all synthesized chlorophyll pigment carries an ethyl group at C-8. Potential reasons for the presence of two 8-vinyl reductases in this strain, which is unique for cyanobacteria, are discussed.IMPORTANCEThe cyanobacteriumAcaryochloris marinais the best-studied phototrophic organism that uses chlorophylldfor photosynthesis. Unique among cyanobacteria sequenced to date, its genome contains ORFs encoding two unrelated enzymes that catalyze the reduction of the C-8 vinyl group of a precursor molecule to an ethyl group. Carrying a reduced C-8 group may be of particular importance to organisms containing chlorophylld. Plant genomes also contain orthologs of both of these genes; thus, the bacterial progenitor of the chloroplast may also have contained bothbciAandbciB.

scholarly journals Two neuronal peptides encoded from a single transcript regulate mitochondrial function in Drosophila

2020 ◽  
Author(s):  
Justin A. Bosch ◽  
Berrak Ugur ◽  
Israel Pichardo-Casas ◽  
Jorden Rabasco ◽  
Felipe Escobedo ◽  
...  
Keyword(s):  
Mitochondrial Function ◽  
Double Mutant ◽  
Open Reading Frames ◽  
Biological Functions ◽  
Neuronal Function ◽  
Phenotypic Analysis ◽  
Single Transcript ◽  
Sequence Similarities ◽  
Reading Frames ◽  
Small Open Reading Frames

SummaryNaturally produced peptides (<100 amino acids) are important regulators of physiology, development, and metabolism. Recent studies have predicted that thousands of peptides may be translated from transcripts containing small open reading frames (smORFs). Here, we describe two previously uncharacterized peptides in Drosophila encoded by conserved smORFs, Sloth1 and Sloth2. These peptides are translated from the same bicistronic transcript and share sequence similarities, suggesting that they encode paralogs. We provide evidence that Sloth1/2 are highly expressed in neurons, localize to mitochondria, and form a complex. Double mutant analysis in animals and cell culture revealed that sloth1 and sloth2 are not functionally redundant, and their loss causes animal lethality, reduced neuronal function, impaired mitochondrial function, and neurodegeneration. These results suggest that phenotypic analysis of smORF genes in Drosophila can provide a wealth of information on the biological functions of this poorly characterized class of genes.

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