scholarly journals Role of arginine‐43 and arginine‐69 of the Hin recombinase catalytic domain in the binding of Hin to the hix DNA recombination sites

1997 ◽  
Vol 24 (6) ◽  
pp. 1235-1247 ◽  
Author(s):  
Curtis W. Adams ◽  
Oliver Nanassy ◽  
Reid C. Johnson ◽  
Kelly T. Hughes
Keyword(s):  
Catalytic Domain ◽  
Dna Recombination ◽  
Hin Recombinase

scholarly journals RAD50 and RAD51 Define Two Pathways That Collaborate to Maintain Telomeres in the Absence of Telomerase

Genetics ◽  
1999 ◽  
Vol 152 (1) ◽  
pp. 143-152 ◽  
Author(s):  
Siyuan Le ◽  
J Kent Moore ◽  
James E Haber ◽  
Carol W Greider
Keyword(s):  
Cell Death ◽  
Telomere Length ◽  
Gene Conversion ◽  
De Novo ◽  
Dna Recombination ◽  
Telomere Maintenance ◽  
Triple Mutant ◽  
Yeast Telomerase ◽  
Telomere Lengthening

Abstract Telomere length is maintained by the de novo addition of telomere repeats by telomerase, yet recombination can elongate telomeres in the absence of telomerase. When the yeast telomerase RNA component, TLC1, is deleted, telomeres shorten and most cells die. However, gene conversion mediated by the RAD52 pathway allows telomere lengthening in rare survivor cells. To further investigate the role of recombination in telomere maintenance, we assayed telomere length and the ability to generate survivors in several isogenic DNA recombination mutants, including rad50, rad51, rad52, rad54, rad57, xrs2, and mre11. The rad51, rad52, rad54, and rad57 mutations increased the rate of cell death in the absence of TLC1. In contrast, although the rad50, xrs2, and mre11 strains initially had short telomeres, double mutants with tlc1 did not affect the rate of cell death, and survivors were generated at later times than tlc1 alone. While none of the double mutants of recombination genes and tlc1 (except rad52 tlc1) blocked the ability to generate survivors, a rad50 rad51 tlc1 triple mutant did not allow the generation of survivors. Thus RAD50 and RAD51 define two separate pathways that collaborate to allow cells to survive in the absence of telomerase.

scholarly journals The crystal structure of Mycobacterium tuberculosis high-temperature requirement A protein reveals an autoregulatory mechanism

2018 ◽  
Vol 74 (12) ◽  
pp. 803-809
Author(s):  
Arvind Kumar Gupta ◽  
Debashree Behera ◽  
Balasubramanian Gopal
Keyword(s):  
Crystal Structure ◽  
Mycobacterium Tuberculosis ◽  
High Temperature ◽  
Catalytic Domain ◽  
Pdz Domain ◽  
Regulatory Pathways ◽  
Inactive Conformation ◽  
Temperature Requirement ◽  
Autoregulatory Mechanism

The crystal structure of Mycobacterium tuberculosis high-temperature requirement A (HtrA) protein was determined at 1.83 Å resolution. This membrane-associated protease is essential for the survival of M. tuberculosis. The crystal structure reveals that interactions between the PDZ domain and the catalytic domain in HtrA lead to an inactive conformation. This finding is consistent with its proposed role as a regulatory protease that is conditionally activated upon appropriate environmental triggers. The structure provides a basis for directed studies to evaluate the role of this essential protein and the regulatory pathways that are influenced by this protease.

scholarly journals Glycogen Phosphorylase in Acanthamoeba spp.: Determining the Role of the Enzyme during the Encystment Process Using RNA Interference

2008 ◽  
Vol 7 (3) ◽  
pp. 509-517 ◽  
Author(s):  
Jacob Lorenzo-Morales ◽  
Jarmila Kliescikova ◽  
Enrique Martinez-Carretero ◽  
Luis Miguel De Pablos ◽  
Bronislava Profotova ◽  
...  
Keyword(s):  
Rna Interference ◽  
Cyst Wall ◽  
Glycogen Phosphorylase ◽  
Catalytic Domain ◽  
Present Report ◽  
Light And Electron Microscopy ◽  
Main Tool ◽  
Lower Eukaryotes ◽  
Free Glucose

ABSTRACT Acanthamoeba infections are difficult to treat due to often late diagnosis and the lack of effective and specific therapeutic agents. The most important reason for unsuccessful therapy seems to be the existence of a double-wall cyst stage that is highly resistant to the available treatments, causing reinfections. The major components of the Acanthamoeba cyst wall are acid-resistant proteins and cellulose. The latter has been reported to be the major component of the inner cyst wall. It has been demonstrated previously that glycogen is the main source of free glucose for the synthesis of cellulose in Acanthamoeba, partly as glycogen levels fall during the encystment process. In other lower eukaryotes (e.g., Dictyostelium discoideum), glycogen phosphorylase has been reported to be the main tool used for glycogen breakdown in order to maintain the free glucose levels during the encystment process. Therefore, it was hypothesized that the regulation of the key processes involved in the Acanthamoeba encystment may be similar to the previously reported regulation mechanisms in other lower eukaryotes. The catalytic domain of the glycogen phosphorylase was silenced using RNA interference methods, and the effect of this phenomenon was assessed by light and electron microscopy analyses, calcofluor staining, expression zymogram assays, and Northern and Western blot analyses of both small interfering RNA-treated and control cells. The present report establishes the role of glycogen phosphorylase during the encystment process of Acanthamoeba. Moreover, the obtained results demonstrate that the enzyme is required for cyst wall assembly, mainly for the formation of the cell wall inner layer.

scholarly journals Chasing Particularities of Guanine- and Cytosine-Rich DNA Strands

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 434 ◽  
Author(s):  
Marko Trajkovski ◽  
Janez Plavec
Keyword(s):  
Structural Changes ◽  
Polyacrylamide Gel Electrophoresis ◽  
Dna Recombination ◽  
Cd Spectroscopy ◽  
G Quadruplex ◽  
Recombination Processes ◽  
Dna Strands ◽  
Native Polyacrylamide Gel Electrophoresis ◽  
Myc Gene

By substitution of natural nucleotides by their abasic analogs (i.e., 1′,2′-dideoxyribose phosphate residue) at critically chosen positions within 27-bp DNA constructs originating from the first intron of N-myc gene, we hindered hybridization within the guanine- and cytosine-rich central region and followed formation of non-canonical structures. The impeded hybridization between the complementary strands leads to time-dependent structural transformations of guanine-rich strand that are herein characterized with the use of solution-state NMR, CD spectroscopy, and native polyacrylamide gel electrophoresis. Moreover, the DNA structural changes involve transformation of intra- into inter-molecular G-quadruplex structures that are thermodynamically favored. Intriguingly, the transition occurs in the presence of complementary cytosine-rich strands highlighting the inability of Watson–Crick base-pairing to preclude the transformation between G-quadruplex structures that occurs via intertwining mechanism and corroborates a role of G-quadruplex structures in DNA recombination processes.

Leukocyte recruitment induced by snake venom metalloproteinases: Role of the catalytic domain

2020 ◽  
Vol 521 (2) ◽  
pp. 402-407
Author(s):  
Bianca Cestari Zychar ◽  
Patrícia Bianca Clissa ◽  
Eneas Carvalho ◽  
Cristiani Baldo ◽  
Luis Roberto C. Gonçalves
Keyword(s):  
Snake Venom ◽  
Catalytic Domain ◽  
Leukocyte Recruitment

Structural chemistry involved in information detection and transmission by gas sensor heme proteins: Resonance Raman investigation

2008 ◽  
Vol 80 (12) ◽  
pp. 2667-2678 ◽  
Author(s):  
Samir F. El-Mashtoly ◽  
Teizo Kitagawa
Keyword(s):  
Gas Sensor ◽  
Structural Changes ◽  
Catalytic Domain ◽  
Signal Transmission ◽  
Resonance Raman ◽  
Protein Activity ◽  
Sensor Proteins ◽  
Vinyl Group ◽  
Protein Moiety

A variety of heme-containing gas sensor proteins have been discovered by gene analysis from bacteria to mammals. In general, these proteins are composed of an N-terminal heme-containing sensor domain and a C-terminal catalytic domain. Binding of O2, CO, or NO to the heme causes a change in the structure of heme, which alters the protein conformation in the vicinity of the heme, and the conformational change is propagated to the catalytic domain, leading to regulation of the protein activity. This mini-review summarizes the recent resonance Raman studies obtained with both visible and UV excitation sources for two O2 sensor proteins, EcDOS and HemAT-Bs. These investigations have shown the role of heme propionate hydrogen-bonding interactions in communicating the heme structural changes, which occur upon ligand binding, from heme to the protein moiety. Furthermore, it is deduced that the contact interactions between the heme 2-vinyl group and the surrounding residues are also important for signal transmission from heme to protein in EcDOS.

scholarly journals The cellodextrinase from Pseudomonas fluorescens subsp. cellulosa consists of multiple functional domains

1991 ◽  
Vol 279 (3) ◽  
pp. 793-799 ◽  
Author(s):  
L M A Ferreira ◽  
G P Hazlewood ◽  
P J Barker ◽  
H J Gilbert
Keyword(s):  
Pseudomonas Fluorescens ◽  
Catalytic Domain ◽  
Genomic Library ◽  
Terminal Region ◽  
Crystalline Cellulose ◽  
Nucleotide Sequencing ◽  
Reading Frame ◽  
Strong Homology ◽  
Cellulose Binding

A genomic library of Pseudomonas fluorescens subsp. cellulosa DNA was constructed in pUC18 and Escherichia coli recombinants expressing 4-methylumbelliferyl beta-D-cellobioside-hydrolysing activity (MUCase) were isolated. Enzyme produced by MUCase-positive clones did not hydrolyse either cellobiose or cellotriose but converted cellotetraose into cellobiose and cleaved cellopentaose and cellohexaose, producing a mixture of cellobiose and cellotriose. There was no activity against CM-cellulose, insoluble cellulose or xylan. On this basis, the enzyme is identified as an endo-acting cellodextrinase and is designated cellodextrinase C (CELC). Nucleotide sequencing of the gene (celC) which directs the synthesis of CELC revealed an open reading frame of 2153 bp, encoding a protein of Mr 80,189. The deduced primary sequence of CELC was confirmed by the Mr of purified CELC (77,000) and by the experimentally determined N-terminus of the enzyme which was identical with residues 38-47 of the translated sequence. The N-terminal region of CELC showed strong homology with endoglucanase, xylanases and an arabinofuranosidase of Ps. fluorescens subsp. cellulosa; homologous sequences included highly conserved serine-rich regions. Full-length CELC bound tightly to crystalline cellulose. Truncated forms of celC from which the DNA sequence encoding the conserved domain had been deleted, directed the synthesis of a functional cellodextrinase that did not bind to crystalline cellulose. This is consistent with the N-terminal region of CELC comprising a non-catalytic cellulose-binding domain which is distinct from the catalytic domain. The role of the cellulose-binding region is discussed.

scholarly journals Thrombin A-Chain: Activation Remnant or Allosteric Effector?

Thrombosis ◽  
2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Isis S. R. Carter ◽  
Amanda L. Vanden Hoek ◽  
Edward L. G. Pryzdial ◽  
Ross T. A. MacGillivray
Keyword(s):  
Biochemical Characterization ◽  
Catalytic Domain ◽  
Current Data ◽  
Enzymatic Reactions ◽  
Allosteric Effector ◽  
Naturally Occurring ◽  
Physiologic Function ◽  
A Chain

Although prothrombin is one of the most widely studied enzymes in biology, the role of the thrombin A-chain has been neglected in comparison to the other domains. This paper summarizes the current data on the prothrombin catalytic domain A-chain region and the subsequent thrombin A-chain. Attention is given to biochemical characterization of naturally occurring prothrombin A-chain mutations and alanine scanning mutants in this region. While originally considered to be simply an activation remnant with little physiologic function, the thrombin A-chain is now thought to play a role as an allosteric effector in enzymatic reactions and may also be a structural scaffold to stabilize the protease domain.

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