Angelov A

References (8)

Title : Novel Flp pilus biogenesis-dependent natural transformation - Angelov_2015_Front.Microbiol_6_84
Author(s) : Angelov A , Bergen P , Nadler F , Hornburg P , Lichev A , Ubelacker M , Pachl F , Kuster B , Liebl W
Ref : Front Microbiol , 6 :84 , 2015
Abstract : Natural transformation has been described in bacterial species spread through nearly all major taxonomic groups. However, the current understanding of the structural components and the regulation of competence development is derived from only a few model organisms. Although natural transformation was discovered in members of the Actinobacteria (high GC Gram-positive bacteria) more than four decades ago, the structural components or the regulation of the competence system have not been studied in any representative of the entire phylum. In this report we identify a new role for a distinct type of pilus biogenesis genes (tad genes, for tight adherence), which so far have been connected only with biofilm formation, adherence and virulence traits. The tad-like genes found in the genome of Micrococcus luteus were shown to be required for genetic transformation in this actinobacterial species. We generated and analyzed individual knockout mutants for every open reading frame of the two predicted tad gene clusters as well as for a potential prepilin processing peptidase and identified the major component of the putative pili. By expressing a tagged variant of the major prepilin subunit and immunofluorescence microscopy we visualized filamentous structures extending from the cell surface. Our data indicate that the two tad gene islands complementarily contribute to the formation of a functional competence pilus in this organism. It seems likely that the involvement of tad genes in natural transformation is not unique only for M. luteus but may also prove to be the case in other representatives of the Actinobacteria, which contains important medically and biotechnologically relevant species.
ESTHER : Angelov_2015_Front.Microbiol_6_84
PubMedSearch : Angelov_2015_Front.Microbiol_6_84
PubMedID: 25713572
Gene_locus related to this paper: miclu-d3lls7

Title : Identification of novel esterase-active enzymes from hot environments by use of the host bacterium Thermus thermophilus - Leis_2015_Front.Microbiol_6_275
Author(s) : Leis B , Angelov A , Mientus M , Li H , Pham VT , Lauinger B , Bongen P , Pietruszka J , Goncalves LG , Santos H , Liebl W
Ref : Front Microbiol , 6 :275 , 2015
Abstract : Functional metagenomic screening strategies, which are independent of known sequence information, can lead to the identification of truly novel genes and enzymes. Since E. coli has been used exhaustively for this purpose as a host, it is important to establish alternative expression hosts and to use them for functional metagenomic screening for new enzymes. In this study we show that Thermus thermophilus HB27 is an excellent screening host and can be used as an alternative provider of truly novel biocatalysts. In a previous study we constructed mutant strain BL03 with multiple markerless deletions in genes for major extra- and intracellular lipolytic activities. This esterase-diminished strain was no longer able to grow on defined minimal medium supplemented with tributyrin as the sole carbon source and could be used as a host to screen for metagenomic DNA fragments that could complement growth on tributyrin. Several thousand single fosmid clones from thermophilic metagenomic libraries from heated compost and hot spring water samples were subjected to a comparative screening for esterase activity in both T. thermophilus strain BL03 and E. coli EPI300. We scored a greater number of active esterase clones in the thermophilic bacterium than in the mesophilic E. coli. From several thousand functionally screened clones only two thermostable alpha/beta-fold hydrolase enzymes with high amino acid sequence similarity to already characterized enzymes were identifiable in E. coli. In contrast, five further fosmids were found that conferred lipolytic activities in T. thermophilus only. Four open reading frames (ORFs) were found which did not share significant similarity to known esterase enzymes but contained the conserved GXSXG motif regularly found in lipolytic enzymes. Two of the genes were expressed in both hosts and the novel thermophilic esterases, which based on their primary structures could not be assigned to known esterase or lipase families, were purified and preliminarily characterized. Our work underscores the benefit of using additional screening hosts other than E. coli for the identification of novel biocatalysts with industrial relevance.
ESTHER : Leis_2015_Front.Microbiol_6_275
PubMedSearch : Leis_2015_Front.Microbiol_6_275
PubMedID: 25904908

Title : Genetic analysis of lipolytic activities in Thermus thermophilus HB27 - Leis_2014_J.Biotechnol_191_150
Author(s) : Leis B , Angelov A , Li H , Liebl W
Ref : J Biotechnol , 191 :150 , 2014
Abstract : The extremely thermophilic bacterium Thermus thermophilus HB27 displays lipolytic activity for the hydrolysis of triglycerides. In this study we performed a mutational in vivo analysis of esterases and lipases that confer growth on tributyrin. We interrupted 10 ORFs suspected to encode lipolytic enzymes. Two chromosomal loci were identified that resulted in reduced hydrolysis capabilities against tributyrin and various para-nitrophenyl acyl esters. By implementation of a convenient new one-step method which abstains from the use of selectable markers, a mutant strain with multiple scar-less deletions was constructed by sequentially deleting ORFs TT_C1787, TT_C0340, TT_C0341 and TT_C0904. The quadruple deletion mutant of T. thermophilus exhibited significantly lower lipolytic activity (approximately 25% residual activity compared to wild type strain) over a broad range of fatty acyl esters and had lost the ability to grow on agar plates containing tributyrin as the sole carbon source. Furthermore, we were able to determine the impact of each gene disruption on the lipolytic activity profile in this model organism and show that the esterase activity in T. thermophilus HB27 is due to a concerted action of several hydrolases having different substrate preferences and activities. The esterase-less T. thermophilus multi-deletion mutant from this study can be used as a screening and expression host for esterase genes from thermophiles or metagenomes.
ESTHER : Leis_2014_J.Biotechnol_191_150
PubMedSearch : Leis_2014_J.Biotechnol_191_150
PubMedID: 25102235

Title : Involvement of two latex-clearing proteins during rubber degradation and insights into the subsequent degradation pathway revealed by the genome sequence of Gordonia polyisoprenivorans strain VH2 - Hiessl_2012_Appl.Environ.Microbiol_78_2874
Author(s) : Hiessl S , Schuldes J , Thurmer A , Halbsguth T , Broker D , Angelov A , Liebl W , Daniel R , Steinbuchel A
Ref : Applied Environmental Microbiology , 78 :2874 , 2012
Abstract : The increasing production of synthetic and natural poly(cis-1,4-isoprene) rubber leads to huge challenges in waste management. Only a few bacteria are known to degrade rubber, and little is known about the mechanism of microbial rubber degradation. The genome of Gordonia polyisoprenivorans strain VH2, which is one of the most effective rubber-degrading bacteria, was sequenced and annotated to elucidate the degradation pathway and other features of this actinomycete. The genome consists of a circular chromosome of 5,669,805 bp and a circular plasmid of 174,494 bp with average GC contents of 67.0% and 65.7%, respectively. It contains 5,110 putative protein-coding sequences, including many candidate genes responsible for rubber degradation and other biotechnically relevant pathways. Furthermore, we detected two homologues of a latex-clearing protein, which is supposed to be a key enzyme in rubber degradation. The deletion of these two genes for the first time revealed clear evidence that latex-clearing protein is essential for the microbial utilization of rubber. Based on the genome sequence, we predict a pathway for the microbial degradation of rubber which is supported by previous and current data on transposon mutagenesis, deletion mutants, applied comparative genomics, and literature search.
ESTHER : Hiessl_2012_Appl.Environ.Microbiol_78_2874
PubMedSearch : Hiessl_2012_Appl.Environ.Microbiol_78_2874
PubMedID: 22327575
Gene_locus related to this paper: gorpv-h6mtj1 , gorpv-h6mzw9 , gorpv-h6n0e3 , gorpv-h6n0g6 , gorpv-h6n0p7 , gorpv-h6mts4 , 9acto-h0rbp9 , 9acto-h0rc96 , gorpv-h6mu09 , gorpv-h6mtj7 , gorpv-h6n352 , gorpv-h6mui9 , gorpv-h6n4w7

Title : Genomic analysis reveals Lactobacillus sanfranciscensis as stable element in traditional sourdoughs - Vogel_2011_Microb.Cell.Fact_10 Suppl 1_S6
Author(s) : Vogel RF , Pavlovic M , Ehrmann MA , Wiezer A , Liesegang H , Offschanka S , Voget S , Angelov A , Bocker G , Liebl W
Ref : Microb Cell Fact , 10 Suppl 1 :S6 , 2011
Abstract : Sourdough has played a significant role in human nutrition and culture for thousands of years and is still of eminent importance for human diet and the bakery industry. Lactobacillus sanfranciscensis is the predominant key bacterium in traditionally fermented sourdoughs.The genome of L. sanfranciscensis TMW 1.1304 isolated from an industrial sourdough fermentation was sequenced with a combined Sanger/454-pyrosequencing approach followed by gap closing by walking on fosmids. The sequencing data revealed a circular chromosomal sequence of 1,298,316 bp and two additional plasmids, pLS1 and pLS2, with sizes of 58,739 bp and 18,715 bp, which are predicted to encode 1,437, 63 and 19 orfs, respectively. The overall GC content of the chromosome is 34.71%. Several specific features appear to contribute to the ability of L. sanfranciscensis to outcompete other bacteria in the fermentation. L. sanfranciscensis contains the smallest genome within the lactobacilli and the highest density of ribosomal RNA operons per Mbp genome among all known genomes of free-living bacteria, which is important for the rapid growth characteristics of the organism. A high frequency of gene inactivation and elimination indicates a process of reductive evolution. The biosynthetic capacity for amino acids scarcely availably in cereals and exopolysaccharides reveal the molecular basis for an autochtonous sourdough organism with potential for further exploitation in functional foods. The presence of two CRISPR/cas loci versus a high number of transposable elements suggests recalcitrance to gene intrusion and high intrinsic genome plasticity.
ESTHER : Vogel_2011_Microb.Cell.Fact_10 Suppl 1_S6
PubMedSearch : Vogel_2011_Microb.Cell.Fact_10 Suppl 1_S6
PubMedID: 21995419

Title : Hyperthermostable acetyl xylan esterase - Drzewiecki_2010_Microb.Biotechnol_3_84
Author(s) : Drzewiecki K , Angelov A , Ballschmiter M , Tiefenbach KJ , Sterner R , Liebl W
Ref : Microb Biotechnol , 3 :84 , 2010
Abstract : An esterase which is encoded within a Thermotoga maritima chromosomal gene cluster for xylan degradation and utilization was characterized after heterologous expression of the corresponding gene in Escherichia coli and purification of the enzyme. The enzyme, designated AxeA, shares amino acid sequence similarity and its broad substrate specificity with the acetyl xylan esterase from Bacillus pumilus, the cephalosporin C deacetylase from Bacillus subtilis, and other (putative) esterases, allowing its classification as a member of carbohydrate esterase family 7. The recombinant enzyme displayed activity with p-nitrophenyl-acetate as well as with various acetylated sugar substrates such as glucose penta-acetate, acetylated oat spelts xylan and DMSO (dimethyl sulfoxide)-extracted beechwood xylan, and with cephalosporin C. Thermotoga maritima AxeA represents the most thermostable acetyl xylan esterase known to date. In a 10 min assay at its optimum pH of 6.5 the enzyme's activity peaked at 90 degrees C. The inactivation half-life of AxeA at a protein concentration of 0.3 microg microl(-1) in the absence of substrate was about 13 h at 98 degrees C and about 67 h at 90 degrees C. Differential scanning calorimetry analysis of the thermal stability of AxeA corroborated its extreme heat resistance. A multi-phasic unfolding behaviour was found, with two apparent exothermic peaks at approximately 100-104 degrees C and 107.5 degrees C. In accordance with the crystal structure, gel filtration analysis at ambient temperature revealed that the enzyme has as a homohexameric oligomerization state, but a dimeric form was also found.
ESTHER : Drzewiecki_2010_Microb.Biotechnol_3_84
PubMedSearch : Drzewiecki_2010_Microb.Biotechnol_3_84
PubMedID: 21255309
Gene_locus related to this paper: thema-TM0077

Title : Genome sequence of the polysaccharide-degrading, thermophilic anaerobe Spirochaeta thermophila DSM 6192 - Angelov_2010_J.Bacteriol_192_6492
Author(s) : Angelov A , Liebl S , Ballschmiter M , Bomeke M , Lehmann R , Liesegang H , Daniel R , Liebl W
Ref : Journal of Bacteriology , 192 :6492 , 2010
Abstract : Spirochaeta thermophila is a thermophilic, free-living anaerobe that is able to degrade various alpha- and beta-linked sugar polymers, including cellulose. We report here the complete genome sequence of S. thermophila DSM 6192, which is the first genome sequence of a thermophilic, free-living member of the Spirochaetes phylum. The genome data reveal a high density of genes encoding enzymes from more than 30 glycoside hydrolase families, a noncellulosomal enzyme system for (hemi)cellulose degradation, and indicate the presence of a novel carbohydrate-binding module.
ESTHER : Angelov_2010_J.Bacteriol_192_6492
PubMedSearch : Angelov_2010_J.Bacteriol_192_6492
PubMedID: 20935097
Gene_locus related to this paper: spitd-e0rq60 , spitd-e0rrc2 , spitd-e0rsy8

Title : Genome sequence of Picrophilus torridus and its implications for life around pH 0 - Futterer_2004_Proc.Natl.Acad.Sci.U.S.A_101_9091
Author(s) : Futterer O , Angelov A , Liesegang H , Gottschalk G , Schleper C , Schepers B , Dock C , Antranikian G , Liebl W
Ref : Proc Natl Acad Sci U S A , 101 :9091 , 2004
Abstract : The euryarchaea Picrophilus torridus and Picrophilus oshimae are able to grow around pH 0 at up to 65 degrees C, thus they represent the most thermoacidophilic organisms known. Several features that may contribute to the thermoacidophilic survival strategy of P. torridus were deduced from analysis of its 1.55-megabase genome. P. torridus has the smallest genome among nonparasitic aerobic microorganisms growing on organic substrates and simultaneously the highest coding density among thermoacidophiles. An exceptionally high ratio of secondary over ATP-consuming primary transport systems demonstrates that the high proton concentration in the surrounding medium is extensively used for transport processes. Certain genes that may be particularly supportive for the extreme lifestyle of P. torridus appear to have been internalized into the genome of the Picrophilus lineage by horizontal gene transfer from crenarchaea and bacteria. Finally, it is noteworthy that the thermoacidophiles from phylogenetically distant branches of the Archaea apparently share an unexpectedly large pool of genes.
ESTHER : Futterer_2004_Proc.Natl.Acad.Sci.U.S.A_101_9091
PubMedSearch : Futterer_2004_Proc.Natl.Acad.Sci.U.S.A_101_9091
PubMedID: 15184674
Gene_locus related to this paper: picto-q6kyx8 , picto-q6kz86 , picto-q6kzp3 , picto-q6kzx6 , picto-q6kzy9 , picto-q6l0c9 , picto-q6l018 , picto-q6l189 , picto-q6l217