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At least 1,369 records · Page 76Linked to original sources
PubMed1990

Purification of a beta-Amylase that Accumulates in Arabidopsis thaliana Mutants Defective in Starch Metabolism.

Amylase activity is elevated 5- to 10-fold in leaves of several different Arabidopsis thaliana mutants defective in starch metabolism when they are grown under a 12-hour photoperiod. Activity is also increased when plants are grown under higher light intensity. It was previously determined that the elevated activity was an extrachloroplastic beta-(exo)amylase. Due to the location of this enzyme outside the chloroplast, its function is not known. The enzyme was purified to homogeneity from leaves of both a starchless mutant deficient in plastid phosphoglucomutase and from the wild type using polyethylene glycol fractionation and cyclohexaamylose affinity chromatography. The molecular mass of the beta-amylase from both sources was 55,000 daltons as determined by denaturing gel electrophoresis. Gel filtration studies indicated that the enzyme was a monomer. The specific activities of the purified protein from mutant and wild-type sources, their substrate specificities, and K(m) for amylopectin were identical. Based on these results it was concluded that the mutant contained an increased level of beta-amylase protein. Enzyme neutralization studies using a polyclonal antiserum raised to purified beta-amylase showed that in each of two starchless mutants, one starch deficient mutant and one starch overproducing mutant, the elevated amylase activity was due to elevated beta-amylase protein.

Journal Article↗
PubMed1990

Response of enzymes and storage proteins of maize endosperm to nitrogen supply.

To examine the effects of N nutrition upon endosperm development, maize (Zea mays) kernels were grown in vitro with either 0, 3.6, 7.1, 14.3, or 35.7 millimolar N. Kernels were harvested at 20 days after pollination for determination of enzyme activities and again at maturity for quantification of storage products and electrophoretic separation of zeins. Endosperm dry weight, starch, zein-N, and nonzein-N all increased in mature kernels as N supply increased from zero to 14.3 millimolar. The activities of sucrose synthase, aldolase, phosphoglucomutase, glutamate-pyruvate transaminase, glutamate-oxaloacetate transaminase, and acetolactate synthase increased from 1- to 2.5-fold with increasing N supply. Adenosine diphosphate-glucose pyrophosphorylase and both ATP- and PPi-dependent phosphofructokinases increased to lesser extents, while no significant response was detected for hexose kinases and glutamine synthetase. Nitrogen-induced changes in enzyme activities were often highly correlated with changes in final starch and/or zein-N contents. Separation of zeins indicated that these peptides were proportionately enhanced by N supply, with the exception of C-zein, which was relatively insensitive to N. These data indicate that at least a portion of the yield increase in maize produced by N fertilization is induced by a modification of kernel metabolism in response to N supply.

Journal Article↗
PubMed1991

A Quantification of the Significance of Assimilatory Starch for Growth of Arabidopsis thaliana L. Heynh.

These studies use starch synthesis mutants to quantify the contribution of assimilatory starch to whole plant growth and form. Arabidopsis thaliana (L.) Heynh plants were used with null plastid phosphoglucomutase (T Caspar, SC Huber, CR Sommerville, [1986] Plant Physiol 79; 1-7) or 7% of wild-type ADP-glucose pyrophosphorylase (T-P Lin, T Caspar, CR Sommerville, J Preiss [1988] Plant Physiol 88; 1175-1179). The daily turnover of starch and the rate of biomass increase in the mutants and the wild type were investigated during growth in a 14 hour light/10 hour dark cycle in high irradiance (600 micromoles per square meter per second) and nitrogen (6 millimolar NH(4)NO(3)), in high irradiance and low nitrogen (0.1 millimolar NH(4)NO(3)) or in low irradiance (80 micromoles per square meter per second) and high nitrogen. There is some variability in the data, but the following conclusions can be drawn. Growth was slow in the absence of starch turnover. In high nitrogen conditions, about 1 mole of carbon per gram dry weight per day was incorporated additionally into structural biomass for every one mole of carbon turned over as starch per gram dry weight per day. In low nitrogen, the gain was much lower. This indicates that temporary storage of photosynthate is important for rapid growth in high nitrogen, but not in low nitrogen when carbohydrate is in excess. Starch-deficient plants showed the usual decrease of the shoot/root ratio in low nitrogen and increase of the ratio in low light. This shows that adjustment of plant form to nitrogen nutrition and irradiance is not mediated via regulation of photosynthate partitioning in the leaf. Starch deficient plants had lower shoot/root ratios than the wild type and the nitrogen concentration in their leaves was increased. It is discussed how interactions between carbohydrate allocation, respiration and growth at the organ and whole plant level generate these changes. We conclude that mutants with a decreased capacity to carry out a particular partial process provide a powerful tool to disect complex mutually interacting systems, and define and quantify causal interactions at the level of whole plant growth.

Journal Article↗
PubMed1992

Evidence for Mitochondrial Regulation of Photosynthesis by a Starchless Mutant of Nicotiana sylvestris.

Mutant NS458 of Nicotiana sylvestris (Speg. et Comes) contains a defective plastid phosphoglucomutase and accumulates only trace amounts of starch. Determinations of carbon partitioning using tracer d-[3-(14)C]glyceric acid showed that the maximal CO(2) assimilation by mature leaves of the mutant at saturating [CO(2)] and light and low [O(2)] was close to the flux for sucrose formation in the wild type. The mutant is characterized by exceptionally slow oscillations in maximal CO(2) assimilation. The postulate that these slow oscillations follow changes in the cytosolic rate of sucrose phosphate synthesis has been investigated. Studies with wild-type and mutant leaf discs subjected to various treatments failed to indicate that any significant activation-inactivation cycle in sucrose-P synthase activity can occur. The rate of sucrose phosphate synthesis, however, might be altered by variations in the supply of uridine UDP-glucose which is controlled by the rate of ATP regeneration (via UTP regeneration). Treating mutant leaf protoplasts and young leaves with oligomycin, an inhibitor of mitochondrial ATP regeneration, reduced photosynthesis by as much as 25 and 40%, respectively. The wild type failed to show inhibition by oligomycin, i.e. its effect is masked when starch and sucrose synthesis can interact. It is concluded that maximal CO(2) assimilation in the mutant is fine tuned by mitochondrial metabolism such that interactions between sucrose synthesis and mitochondrial processes may generate the observed oscillations.

Journal Article↗
PubMed1992

Photosynthate metabolism in the source leaves of n(2)-fixing soybean plants.

Soybean plants (Glycine max [L.] Merr. cv Williams), which were symbiotic with Bradyrhizobium japonicum, and which grew well upon reduced nitrogen supplied solely through N(2) fixation processes, often exhibited excess accumulation of starch and sucrose and diminished soluble protein in their source leaves. Nitrate and ammonia, when supplied to the nodulated roots of N(2)-fixing plants, mediated a reduction of foliar starch accumulation and a corresponding increase in soluble protein in the source leaves. This provided an opportunity to examine the potential metabolic adjustments by which NO(3) (-) and NH(4) (+) (N) sufficiency or deficiency exerted an influence upon soybean leaf starch synthesis. When compared with soybean plants supplied with N, elevated starch accumulation was focused in leaf palisade parenchyma tissue of N(2)-fixing plants. Foliar activities of starch synthesis pathway enzymes including fructose-1,6-bisphosphate phosphatase, phosphohexoisomerase, phosphoglucomutase (PGM), as well as adenosine diphosphate glucose pyrophosphorylase (in some leaves) exhibited highest activities in leaf extracts of N(2)-fixing plants when expressed on a leaf protein basis. This was interpreted to mean that there was an adaptation of these enzyme activities in the leaves of N(2)-fixing plants, and this contributed to an increase in starch accumulation. Another major causal factor associated with increased starch accumulation was the elevation in foliar levels of fructose-6-phosphate, glucose-6-phosphate, and glucose-1-phosphate (G1P), which had risen to chloroplast concentrations considerably in excess of the K(m) values for their respective target enzymes associated with starch synthesis, e.g. elevated G1P with respect to adenosine diphosphate glucose pyrophosphorylase (ADPG-PPiase) binding sites. The cofactor glucose-1,6-bisphosphate (G1,6BP) was found to be obligate for maximal PGM activity in soybean leaf extracts of N(2)-fixing as well as N-supplemented plants, and G1,6BP levels in N(2)-fixing plant leaves was twice that of levels in N-supplied treatments. However the concentration of chloroplastic G1,6BP in illuminated leaves was computed to be saturating with respect to PGM in both N(2)-fixing and N-supplemented plants. This suggested that the higher level of this cofactor in N(2)-fixing plant leaves did not confer any higher PGM activation and was not a factor in higher starch synthesis rates. Relative to plants supplied with NO(3) (-) and NH(4) (+), the source leaf glycerate-3-phosphate (3-PGA) and orthophosphate (Pi) concentrations in leaves of N(2)-fixing plants were two to four times higher. Although Pi is a physiological competitive inhibitor of leaf chloroplast ADPG-PPiase, and hence, starch synthesis, elevated chloroplast 3-PGA levels in N(2)-fixing plant leaves apparently prevented interference of Pi with ADPG-PPiase catalysis and starch synthesis.

Journal Article↗
PubMed1992

Carbon Partitioning and Growth of a Starchless Mutant of Nicotiana sylvestris.

We have further characterized the photosynthetic carbohydrate metabolism and growth of a starchless mutant (NS 458) of Nicotiana sylvestris that is deficient in plastid phosphoglucomutase (Hanson KR, McHale NA [1988] Plant Physiol 88: 838-844). In general, the mutant had only slightly lower rates of photosynthesis under ambient conditions than the wild type. However, accumulation of soluble sugars (primarily hexose sugars) in source leaves of the mutant compensated for only about half of the carbon stored as starch in the wild type. Therefore, the export rate was slightly higher in the mutant relative to the wild type. Starch in the wild type and soluble sugars in the mutant were used to support plant growth at night. Growth of the mutant was progressively restricted, relative to wild type, when plants were grown under shortened photoperiods. When grown under short days, leaf expansion of the mutant was greater during the day, but was restricted at night relative to wild-type leaves, which expanded primarily at night. We postulate that restricted growth of the mutant on short days is the result of several factors, including slightly lower net photosynthesis and inability to synthesize starch in both source and sink tissues for use at night. In short-term experiments, increased "sink demand" on a source leaf (by shading all other source leaves) had no immediate effect on starch accumulation during the photoperiod in the wild type or on soluble sugar accumulation in the mutant. These results would be consistent with a transport limitation in N. sylvestris such that not all of the additional carbon flux into sucrose in the mutant can be exported from the leaf. Consequently, the mutant accumulates hexose sugars during the photoperiod, apparently as the result of sucrose hydrolysis within the vacuole by acid invertase.

Journal Article↗
PubMed2004

A Robot-based platform to measure multiple enzyme activities in Arabidopsis using a set of cycling assays: comparison of changes of enzyme activities and transcript levels during diurnal cycles and in prolonged darkness.

A platform has been developed to measure the activity of 23 enzymes that are involved in central carbon and nitrogen metabolism in Arabidopsis thaliana. Activities are assayed in optimized stopped assays and the product then determined using a suite of enzyme cycling assays. The platform requires inexpensive equipment, is organized in a modular manner to optimize logistics, calculates results automatically, combines high sensitivity with throughput, can be robotized, and has a throughput of three to four activities in 100 samples per person/day. Several of the assays, including those for sucrose phosphate synthase, ADP glucose pyrophosphorylase (AGPase), ferredoxin-dependent glutamate synthase, glycerokinase, and shikimate dehydrogenase, provide large advantages over previous approaches. This platform was used to analyze the diurnal changes of enzyme activities in wild-type Columbia-0 (Col-0) and the starchless plastid phosphoglucomutase (pgm) mutant, and in Col-0 during a prolongation of the night. The changes of enzyme activities were compared with the changes of transcript levels determined with the Affymetrix ATH1 array. Changes of transcript levels typically led to strongly damped changes of enzyme activity. There was no relation between the amplitudes of the diurnal changes of transcript and enzyme activity. The largest diurnal changes in activity were found for AGPase and nitrate reductase. Examination of the data and comparison with the literature indicated that these are mainly because of posttranslational regulation. The changes of enzyme activity are also strongly delayed, with the delay varying from enzyme to enzyme. It is proposed that enzyme activities provide a quasi-stable integration of regulation at several levels and provide useful data for the characterization and diagnosis of different physiological states. As an illustration, a decision tree constructed using data from Col-0 during diurnal changes and a prolonged dark treatment was used to show that, irrespective of the time of harvest during the diurnal cycle, the pgm mutant resembles a wild-type plant that has been exposed to a 3 d prolongation of the night.

Arabidopsis↗
PubMed2005

Sugars and circadian regulation make major contributions to the global regulation of diurnal gene expression in Arabidopsis.

The diurnal cycle strongly influences many plant metabolic and physiological processes. Arabidopsis thaliana rosettes were harvested six times during 12-h-light/12-h-dark treatments to investigate changes in gene expression using ATH1 arrays. Diagnostic gene sets were identified from published or in-house expression profiles of the response to light, sugar, nitrogen, and water deficit in seedlings and 4 h of darkness or illumination at ambient or compensation point [CO(2)]. Many sugar-responsive genes showed large diurnal expression changes, whose timing matched that of the diurnal changes of sugars. A set of circadian-regulated genes also showed large diurnal changes in expression. Comparison of published results from a free-running cycle with the diurnal changes in Columbia-0 (Col-0) and the starchless phosphoglucomutase (pgm) mutant indicated that sugars modify the expression of up to half of the clock-regulated genes. Principle component analysis identified genes that make large contributions to diurnal changes and confirmed that sugar and circadian regulation are the major inputs in Col-0 but that sugars dominate the response in pgm. Most of the changes in pgm are triggered by low sugar levels during the night rather than high levels in the light, highlighting the importance of responses to low sugar in diurnal gene regulation. We identified a set of candidate regulatory genes that show robust responses to alterations in sugar levels and change markedly during the diurnal cycle.

Arabidopsis↗
PubMed1995

Monogenic Recessive Mutations Causing Both Late Floral Initiation and Excess Starch Accumulation in Arabidopsis.

A recessive Arabidopsis mutation, carbohydrate accumulation mutant1 (cam1), which maps to position 22.8 on chromosome 3, was identified by screening leaves of ethyl methanesulfonate-mutagenized M2 plants stained with iodine for altered starch content. Increased starch content in leaves of the cam1 mutant was observed at the onset of flowering. This mutant also had a delayed floral initiation phenotype with more rosette leaves than the parental line. In addition, activities of several enzymes associated with starch metabolism were altered in the cam1 mutant. The late-flowering mutant gigantea (gi) also manifested an elevated starch level in leaves. However, not all late-flowering mutants had increased leaf starch content. Double mutants cam1 adg1 (for ADP-glucose pyrophosphorylase), cam1 pgm (for phosphoglucomutase), and gi pgm had no observable starch in leaves but showed the late-flowering phenotype, demonstrating that the elevated starch content is not the cause of late floral initiation. The pleiotropic effects of cam1 and gi suggest that they may play regulatory roles in starch metabolism and floral initiation. These data suggest that starch accumulation and floral initiation may share a common regulatory pathway.

Journal Article↗
PubMed1978

Protein polymorphism and geographic variation in the loach Misgurnus anguillicaudatus.

Electrophoretic variations of enzymatic and non-enzymatic proteins were investigated in 8 populations of the loach Misgurnus anguillicaudatus. The cathodic hemoglobin and the muscle protein in the region II were shown to be polymorphic, in addition to the five polymorphic proteins previously reported (the anodic hemoglobin, muscle protein in the region III, 6-phosphogluconate dehydrogenase, phosphoglucomutase and aspartate aminotransferase; Kimura, 1976 & 1977). The muscle proteins in the regions I, IV and V were monomorphic. The values of genetic distances between loach populations, calculated over 10 loci, indicated that M anguillicaudatus should be classified into two local races.

Animals↗
PubMed1987

Search for genetic variation in the blood of Norwegian dairy goats reveals a new polymorphism at the Hb beta A locus.

A total of 150 blood samples tested for serum albumin and transferrin and for red cell carbonic anhydrase, phosphoglucomutase, phosphogluconate dehydrogenase, phosphohexose isomerase, nucleoside phosphorylase, acid phosphatase, 'X'-protein and potassium concentration only showed variation at the 'X' protein and nucleoside phosphorylase loci. Isoelectric focusing over pH range 6-8 showed 145 samples to be of haemoglobin type A and 5 type AD. The haemoglobin A type was resolved into further types by separation over pH 6.9-7.5 in Immobiline polyacrylamide gels. A 2- or 4-band pattern was present in 136 of the samples; a genetic hypothesis based on four or more different haemoglobin A variants is proposed. 14 samples had a 3-, 5- or 6-band pattern. It is assumed that these are heterozygous for a variant of the II alpha gene.

Animals↗
PubMed1988

Genetic variation in the blood of llamas, Llama glama, and alpacas, Llama pacos.

Blood samples of llamas and alpacas were typed using haemolytic, electrophoretic and isoelectric focusing procedures to assay polymorphism at 13 loci. Blood group variation was assessed using six antibody specificities produced by allo- and heteroimmunizations. Two red cell factors (A and B) behave as autosomal, codominant alleles at a closed A locus. The other four factors (C, D, E and F) behave as autosomal, dominant traits. Biochemical variation was found for red cell enzymes catalase, phosphogluconate dehydrogenase, glucose phosphate isomerase and for plasma proteins transferrin and post-albumin. No variants were found for haemoglobin, phosphoglucomutase and albumin. Estimates of probability of exclusion were 0.883 for llamas and 0.681 for alpacas, which are adequate initial levels of efficacy for purposes of parentage verification. Preliminary estimate of Nei's genetic distance measure (D) suggests that llamas and alpacas are more likely related as subspecies than as separate species.

Alleles↗
PubMed1995

Synteny-mapping horse microsatellite markers using a heterohybridoma panel.

A panel of horse-mouse heterohybridoma cells was tested for genetic markers using biochemical and polymerase chain reaction-(PCR-) based tests. Biochemical markers included phosphoglucomutase (PGM), glucose phosphate isomerase (GPI) and 6-phosphogluconate dehydrogenase (PGD). Markers detected using PCR-based tests included microsatellite markers HTG2-15, HMS 1-3, 5-8, VHL20, ECA2 and genes for equine major histocompatibility gene ELA-DRA, tumour necrosis factor alpha (TNFA) and transferrin. The results were analysed for correlation and concordance. Based on the results, five synteny groups were identified, specifically between ELA-DRA, TNFA, HMS5 and HTG5; between HTG3 and HTG13; between HTG4, HTG8 and HMS3; between HTG6 and HMS1; and between HTG7, HTG9 and HMS6. Evidence was also found for synteny between HTG12, HMS7 and ECA2, however, confirmation requires further testing. Cytogenetic evaluation of the cell lines making up the panel indicated that large metacentric chromosomes were preferentially lost or tended to break at the centromere. Consequently, the results from this analysis can be used to identify synteny, but not to exclude synteny.

Animals↗
PubMed1997

Mapping 28 erythrocyte antigen, plasma protein and enzyme polymorphisms using an efficient genomic scan of the porcine genome.

One hundred and fifty-four microsatellite markers were selected for genomic scanning of the porcine genome and were grouped into amplification sets to reduce the cost and labour required. Thirty amplification sets had two markers (duplex), 20 sets had three markers (triplex) and five sets had four markers (quadruplex) while 14 markers were analysed separately. The selection criteria for microsatellites were: ease of scoring, level of polymorphism, genetic location and ability to be genotyped in a multiplexed polymerase chain reaction (PCR). The selected microsatellites were chosen to span the entire genome flanked by the porcine linkage map with intervals between adjacent markers of 15-20 cM where possible. The utility of this set of markers was demonstrated by linkage analyses with loci controlling blood plasma protein and red cell enzyme polymorphisms (n = 13), erythrocyte antigens (n = 15), the S blood group, coat colour and ryanodine receptor from 174 backcross Meishan-White Composite pigs. These loci displayed various forms of inheritance and most (24 loci) have been placed in linkage groups. Significant two-point linkages (lod > 3.0) were detected for each polymorphic marker. These results provide the first linkage assignments for phosphoglucomutase (PGM2) and erythrocyte antigen F (EAF) to SSC8; and serum amylase (AMY) and erythrocyte antigen I (EAI) to SSC18. All of the remaining polymorphic loci (n = 24) mapped to previously identified regions confirming earlier results. Most of the markers used in this study should be useful in resource populations of various breed crosses as the number of alleles detected in a multibreed reference population was one of the selection criteria.

Animals↗
PubMed1975

Acquired erythroenzymopathies in blood disorders: study of 200 cases.

Enzyme abnormalities are frequently found in the red cells of patients with various acquired blood disorders. In leukaemias, preleukaemic states and bone marrow insufficiencies with or without sideroblastosis, changes in enzyme activity are usually characterized by the coexistence of deficiency of some enzymes and an increased activity of others. The most frequently decreased activities are those of pyruvate kinase, phosphofructokinase,2,3-diphosphoglycerate mutase and adenylate kinase; the most frequently increased activities are those of hexokinase, aldolase, enolase, 6-phosphogluconate dehydrogenase and glucose-6-phosphate dehydrogenase. In primary myelofibrosis and in polycythaemia rubra vera, enzyme deficiencies are infrequent and differ from those observed in leukaemias and related disorders. Phosphohexose isomerase and phosphoglucomutase deficiencies seem relatively specific for polycythaemia rubra vera. Explanations for the acquired enzymopathies are still at the stage of hypothesis. The theory of multiple genetic damage may explain some findings but has not yet been proved right. The possibility of post-translational molecular modification is suggested as a working hypothesis.

Anemia, Aplastic↗
PubMed2005

Maltose utilization in Enterococcus faecalis.

AIMS: The aim of this research was to characterize the metabolic pathway for maltose utilization in Enterococcus faecalis. METHODS AND RESULTS: Screening a library of Enterococcus faecalis insertional mutants allowed the isolation of mutants affected in maltose utilization. Genetic analysis of the insertion loci revealed insertions in neighbour genes encoding an EII component of a phosphotransferase system (PTS) transporter (malT) and a maltose phosphorylase homologue (malP). The malP gene forms part of an operon which also includes genes encoding a phosphoglucomutase (malB), a mutarotase (aldose 1-epimerase) (malM) and a transcriptional regulator (malR). Analysis of (14)C-labelled carbohydrates uptake revealed that more than 97% of maltose enters the cells by the PTS transporter MalT. CONCLUSIONS: Both experimental data and genetic organization of the malPBMR operon strongly suggest that in Enterococcus faecalis, maltose enters using a PTS, leaving maltose-6-phosphate inside the cells which is hydrolysed by a maltose phosphate phosphorylase (MalP). SIGNIFICANCE AND IMPACT OF THE STUDY: This study describes a new pathway for maltose utilization in lactic acid bacteria.

Base Sequence↗
PubMed1994

Genetics of two colonies of Glossina pallidipes originating from allopatric populations in Kenya.

Two large colonies, originating from allopatric populations of Glossina pallidipes Austen, in the Shimba Hills and Nguruman, Kenya, which differ biologically and with respect to vectorial competence, were compared at fourteen enzyme loci using polyacrylamide gel electrophoresis. The colonies had similar levels of genetic diversity with approximately half of the loci being polymorphic, an average of 1.6-1.7 alleles per locus, and a mean heterozygosity per locus of approximately 18.4%. However, the colonies differed significantly in allele frequencies at the loci for phosphoglucomutase, glucose-6-phosphate dehydrogenase, xanthine oxidase, octanol dehydrogenase and phosphoglucose isomerase. The results were compared with earlier studies on this species and no evidence was found for selection of specific alleles during establishment or maintenance of colonies of G. pallidipes, nor were specific chromosomes, or marker genes, associated with the biological differences between the two colonies.

Alleles↗
PubMed2005

A genetic selection for supercoiling mutants of Escherichia coli reveals proteins implicated in chromosome structure.

Chromosomes are divided into topologically independent regions, called domains, by the action of uncharacterized barriers. With the goal of identifying domain barrier components, we designed a genetic selection for mutants with reduced negative supercoiling of the Escherichia coli chromosome. We employed a strain that contained two chromosomally located reporter genes under the control of a supercoiling-sensitive promoter and used transposon mutagenesis to generate a wide range of mutants. We subjected the selected mutants to a series of secondary screens and identified five proteins as modulators of chromosomal supercoiling in vivo. Three of these proteins: H-NS, Fis and DksA, have clear ties to chromosome biology. The other two proteins, phosphoglucomutase (Pgm) and transketolase (TktA), are enzymes involved in carbohydrate metabolism and have not previously been shown to affect DNA. Deletion of any of the identified genes specifically affected chromosome topology, without affecting plasmid supercoiling. We suggest that at least H-NS, Fis and perhaps TktA assist directly in the supercoiling of domains by forming topological barriers on the E. coli chromosome.

Bacterial Proteins↗