Papers by Karolina L. Tkaczuk
BMC Molecular Biology, 2006
Background: Naturally occurring tRNAs contain numerous modified nucleosides. They are formed by e... more Background: Naturally occurring tRNAs contain numerous modified nucleosides. They are formed by enzymatic modification of the primary transcripts during the complex RNA maturation process. In model organisms Escherichia coli and Saccharomyces cerevisiae most enzymes involved in this process have been identified. Interestingly, it was found that tRNA methylation, one of the most common modifications, can be introduced by S-adenosyl-L-methionine (AdoMet)-dependent methyltransferases (MTases) that belong to two structurally and phylogenetically unrelated protein superfamilies: RFM and SPOUT.
Polish journal of microbiology / Polskie Towarzystwo Mikrobiologów = The Polish Society of Microbiologists, 2009
In this work, we present the construction of a metagenomic library in Escherichia coli using pUC1... more In this work, we present the construction of a metagenomic library in Escherichia coli using pUC19 vector and environmental DNA directly isolated from Antarctic topsoil and screened for lipolytic enzymes. Screening on agar supplemented with olive oil and rhodamine B revealed one clone with lipolytic activity (Lip1) out of 1000 E. coli clones. This clone harbored a plasmid, pLip1, which has an insert of 4722 bp that was completely sequenced from both directions. Further analysis of the insert showed three open reading frames (ORFs). ORF2 encoded a protein (Lip1 ) of 469 amino acids with 93% identity to the uncultured Pseudomonas sp. lipase LipJ03. Amino acid sequence comparison and phylogenetic analysis indicated that Lip1 lipase was closely related to family I subfamily 3. Furthermore, we present a three-dimensional model of lipase Lip1 which was generated based on the two known structures of mesophilic lipases from Pseudomonas sp. MIS 38 (PML lipase, PDB; 2Z8X) and Serratia marcesc...
Nature, 2005
ABSTRACT Student beats nerves to turn a poster into a presentation
Acta Crystallographica Section F Structural Biology and Crystallization Communications, 2013
Nucleic Acids Research, 2008
N 1 -methylation of adenosine to m 1 A occurs in several different positions in tRNAs from variou... more N 1 -methylation of adenosine to m 1 A occurs in several different positions in tRNAs from various organisms. A methyl group at position N 1 prevents Watson-Crick-type base pairing by adenosine and is therefore important for regulation of structure and stability of tRNA molecules. Thus far, only one family of genes encoding enzymes responsible for m 1 A methylation at position 58 has been identified, while other m 1 A methyltransferases (MTases) remain elusive. Here, we show that Bacillus subtilis open reading frame yqfN is necessary and sufficient for N 1 -adenosine methylation at position 22 of bacterial tRNA. Thus, we propose to rename YqfN as TrmK, according to the traditional nomenclature for bacterial tRNA MTases, or TrMet(m 1 A22) according to the nomenclature from the MODOMICS database of RNA modification enzymes. tRNAs purified from a "trmK strain are a good substrate in vitro for the recombinant TrmK protein, which is sufficient for m 1 A methylation at position 22 as are tRNAs from Escherichia coli, which natively lacks m 1 A22. TrmK is conserved in Gram-positive bacteria and present in some Gram-negative bacteria, but its orthologs are apparently absent from archaea and eukaryota. Protein structure prediction indicates that the active site of TrmK does not resemble the active site of the m 1 A58 MTase TrmI, suggesting that these two enzymatic activities evolved independently.
Nucleic Acids Research, 2010
Sgm (Sisomicin-gentamicin methyltransferase) from antibiotic-producing bacterium Micromonospora z... more Sgm (Sisomicin-gentamicin methyltransferase) from antibiotic-producing bacterium Micromonospora zionensis is an enzyme that confers resistance to aminoglycosides like gentamicin and sisomicin by specifically methylating G1405 in bacterial 16S rRNA. Sgm belongs to the aminoglycoside resistance methyltransferase (Arm) family of enzymes that have been recently found to spread by horizontal gene transfer among disease-causing bacteria. Structural characterization of Arm enzymes is the key to understand their mechanism of action and to develop inhibitors that would block their activity. Here we report the structure of Sgm in complex with cofactors S-adenosylmethionine (AdoMet) and S-adenosylhomocysteine (AdoHcy) at 2.0 and 2.1 Å resolution, respectively, and results of mutagenesis and rRNA footprinting, and protein-substrate docking. We propose the mechanism of methylation of G1405 by Sgm and compare it with other m 7 G methyltransferases, revealing a surprising diversity of active sites and binding modes for the same basic reaction of RNA modification. This analysis can serve as a stepping stone towards developing drugs that would specifically block the activity of Arm methyltransferases and thereby re-sensitize pathogenic bacteria to aminoglycoside antibiotics.
This study describes the structure of the putative ABC-type 2 transporter TM0543 from Thermotoga ... more This study describes the structure of the putative ABC-type 2 transporter TM0543 from Thermotoga maritima MSB8 determined at a resolution of 2.3 Å. In comparative sequence-clustering analysis, TM0543 displays similarity to NatAB-like proteins, which are components of the ABC-type Na+ efflux pump permease. However, the overall structure fold of the predicted nucleotide-binding domain reveals that it is different from any known structure of ABC-type efflux transporters solved to date. The structure of the putative TM0543 domain also exhibits different dimer architecture and topology of its presumed ATP binding pocket, which may indicate that it does not bind nucleotide at all. Structural analysis of calcium ion binding sites found at the interface between TM0543 dimer subunits suggests that protein may be involved in ion-transporting activity. A detailed analysis of the protein sequence and structure is presented and discussed.
We report a 2.0 Å structure of the CAE31940 protein, a proteobacterial NMT1/THI5-like domain-cont... more We report a 2.0 Å structure of the CAE31940 protein, a proteobacterial NMT1/THI5-like domain-containing protein. We also discuss the primary and tertiary structure similarity with its homologs. The highly conserved FGGXMP motif was identified in CAE31940, which corresponds to the GCCCX motif located in the vicinity of the active center characteristic for THi5-like proteins found in yeast. This suggests that the FGGXMP motif may be a unique hallmark of proteobacterial NMT1/THI5-like proteins.
We present the crystal structures of two universal stress proteins (USP) from Archaeoglobus fulgi... more We present the crystal structures of two universal stress proteins (USP) from Archaeoglobus fulgidus and Nitrosomonas europaea in both apo- and ligand-bound forms. This work is the first complete synthesis of the structural properties of 26 USP available in the Protein Data Bank, over 75% of which were determined by structure genomics centers with no additional information provided. The results of bioinformatic analyses of all available USP structures and their sequence homologs revealed that these two new USP structures share overall structural similarity with structures of USPs previously determined. Clustering and cladogram analyses, however, show how they diverge from other members of the USP superfamily and show greater similarity to USPs from organisms inhabiting extreme environments. We compared them with other archaeal and bacterial USPs and discuss their similarities and differences in context of structure, sequential motifs, and potential function. We also attempted to group all analyzed USPs into families, so that assignment of the potential function to those with no experimental data available would be possible by extrapolation.
KEYWORDS:
Archaeoglobus fulgidus; Nitrosomonas europaea; crystal structures; pathogens; sequence analyses; structural comparison; structural genomics; universal stress protein
Phosphoglycerate kinase (PGK) is indispensable during glycolysis for anaerobic glucose degradatio... more Phosphoglycerate kinase (PGK) is indispensable during glycolysis for anaerobic glucose degradation and energy generation. Here we present comprehensive structure analysis of two putative PGKs from Bacillus anthracis str. Sterne and Campylobacter jejuni in the context of their structural homologs. They are the first PGKs from pathogenic bacteria reported in the Protein Data Bank. The crystal structure of PGK from Bacillus anthracis str. Sterne (BaPGK) has been determined at 1.68 Å while the structure of PGK from Campylobacter jejuni (CjPGK) has been determined at 2.14 Å resolution. The proteins’ monomers are composed of two domains, each containing a Rossmann fold, hinged together by a helix which can be used to adjust the relative position between two domains. It is also shown that apo-forms of both BaPGK and CjPGK adopt open conformations as compared to the substrate and ATP bound forms of PGK from other species.
Isochorismatase-like hydrolases (IHL) constitute a large family of enzymes divided into five stru... more Isochorismatase-like hydrolases (IHL) constitute a large family of enzymes divided into five structural families (by SCOP). IHLs are crucial for siderophore-mediated ferric iron acquisition by cells. Knowledge of the structural characteristics of these molecules will enhance the understanding of the molecular basis of iron transport, and perhaps resolve which of the mechanisms previously proposed in the literature is the correct one. We determined the crystal structure of the apo-form of a putative isochorismatase hydrolase OaIHL (PDB code: 3LQY) from the antarctic γ-proteobacterium Oleispira antarctica, and did comparative sequential and structural analysis of its closest homologs. The characteristic features of all analyzed structures were identified and discussed. We also docked isochorismate to the determined crystal structure by in silico methods, to highlight the interactions of the active center with the substrate. The putative isochorismate hydrolase OaIHL from O. antarctica possesses the typical catalytic triad for IHL proteins. Its active center resembles those IHLs with a D–K–C catalytic triad, rather than those variants with a D–K–X triad. OaIHL shares some structural and sequential features with other members of the IHL superfamily. In silico docking results showed that despite small differences in active site composition, isochorismate binds to in the structure of OaIHL in a similar mode to its binding in phenazine biosynthesis protein PhzD (PDB code 1NF8).
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Papers by Karolina L. Tkaczuk
KEYWORDS:
Archaeoglobus fulgidus; Nitrosomonas europaea; crystal structures; pathogens; sequence analyses; structural comparison; structural genomics; universal stress protein
KEYWORDS:
Archaeoglobus fulgidus; Nitrosomonas europaea; crystal structures; pathogens; sequence analyses; structural comparison; structural genomics; universal stress protein