scholarly journals Engineering and crystal structure of a monomeric FLT3 ligand variant

2021 ◽  
Vol 77 (4) ◽  
pp. 121-127
Author(s):  
Erwin Pannecoucke ◽  
Laurens Raes ◽  
Savvas N. Savvides
Keyword(s):  
Crystal Structure ◽  
Tyrosine Kinases ◽  
Structural Studies ◽  
Flt3 Ligand ◽  
Class Iii ◽  
Wild Type ◽  
Dimer Interface ◽  
Assembly Mechanism ◽  
Receptor Interactions ◽  
Dimerization Interface

The overarching paradigm for the activation of class III and V receptor tyrosine kinases (RTKs) prescribes cytokine-mediated dimerization of the receptor ectodomains and homotypic receptor–receptor interactions. However, structural studies have shown that the hematopoietic receptor FLT3, a class III RTK, does not appear to engage in such receptor–receptor contacts, despite its efficient dimerization by dimeric FLT3 ligand (FL). As part of efforts to better understand the intricacies of FLT3 activation, we sought to engineer a monomeric FL. It was found that a Leu27Asp substitution at the dimer interface of the cytokine led to a stable monomeric cytokine (FLL27D) without abrogation of receptor binding. The crystal structure of FLL27D at 1.65 Å resolution revealed that the introduced point mutation led to shielding of the hydrophobic footprint of the dimerization interface in wild-type FL without affecting the conformation of the FLT3 binding site. Thus, FLL27D can serve as a monomeric FL variant to further interrogate the assembly mechanism of extracellular complexes of FLT3 in physiology and disease.

scholarly journals Structural and Drug Targeting Insights on Mutant p53

Cancers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 3344
Author(s):  
Ana Sara Gomes ◽  
Helena Ramos ◽  
Alberto Inga ◽  
Emília Sousa ◽  
Lucília Saraiva
Keyword(s):  
Small Molecules ◽  
Drug Targeting ◽  
Normal Function ◽  
Structure Stability ◽  
Mutant P53 ◽  
Structural Studies ◽  
Wild Type ◽  
Tumor Onset ◽  
Long Time ◽  
Stability Dynamics

p53 is a transcription factor with a pivotal role in cell homeostasis and fate. Its impairment is a major event in tumor onset and development. In fact, about half of human cancers bear TP53 mutations that not only halt the normal function of p53, but also may acquire oncogenic gain of functions that favor tumorigenesis. Although considered undruggable for a long time, evidence has proven the capability of many compounds to restore a wild-type (wt)-like function to mutant p53 (mutp53). However, they have not reached the clinic to date. Structural studies have strongly contributed to the knowledge about p53 structure, stability, dynamics, function, and regulation. Importantly, they have afforded relevant insights into wt and mutp53 pharmacology at molecular levels, fostering the design and development of p53-targeted anticancer therapies. Herein, we provide an integrated view of mutp53 regulation, particularly focusing on mutp53 structural traits and on targeting agents capable of its reactivation, including their biological, biochemical and biophysical features. With this, we expect to pave the way for the development of improved small molecules that may advance precision cancer therapy by targeting p53.

scholarly journals Host-Selected Amino Acid Changes at the Sialic Acid Binding Pocket of the Parvovirus Capsid Modulate Cell Binding Affinity and Determine Virulence

2006 ◽  
Vol 80 (3) ◽  
pp. 1563-1573 ◽  
Author(s):  
Alberto López-Bueno ◽  
Mari-Paz Rubio ◽  
Nathan Bryant ◽  
Robert McKenna ◽  
Mavis Agbandje-McKenna ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Sialic Acid ◽  
Parallel Evolution ◽  
Attachment Site ◽  
Fibroblast Cell ◽  
Scid Mice ◽  
Wild Type ◽  
Large Plaque ◽  
Capsid Sequence

ABSTRACT The role of receptor recognition in the emergence of virulent viruses was investigated in the infection of severe combined immunodeficient (SCID) mice by the apathogenic prototype strain of the parvovirus minute virus of mice (MVMp). Genetic analysis of isolated MVMp viral clones (n = 48) emerging in mice, including lethal variants, showed only one of three single changes (V325M, I362S, or K368R) in the common sequence of the two capsid proteins. As was found for the parental isolates, the constructed recombinant viruses harboring the I362S or the K368R single substitutions in the capsid sequence, or mutations at both sites, showed a large-plaque phenotype and lower avidity than the wild type for cells in the cytotoxic interaction with two permissive fibroblast cell lines in vitro and caused a lethal disease in SCID mice when inoculated by the natural oronasal route. Significantly, the productive adsorption of MVMp variants carrying any of the three mutations selected through parallel evolution in mice showed higher sensitivity to the treatment of cells by neuraminidase than that of the wild type, indicating a lower affinity of the viral particle for the sialic acid component of the receptor. Consistent with this, the X-ray crystal structure of the MVMp capsids soaked with sialic acid (N-acetyl neuraminic acid) showed the sugar allocated in the depression at the twofold axis of symmetry (termed the dimple), immediately adjacent to residues I362 and K368, which are located on the wall of the dimple, and approximately 22 Å away from V325 in a threefold-related monomer. This is the first reported crystal structure identifying an infectious receptor attachment site on a parvovirus capsid. We conclude that the affinity of the interactions of sialic-acid-containing receptors with residues at or surrounding the dimple can evolutionarily regulate parvovirus pathogenicity and adaptation to new hosts.

scholarly journals The Synechococcus Strain PCC 7942glnN Product (Glutamine Synthetase III) Helps Recovery from Prolonged Nitrogen Chlorosis

2000 ◽  
Vol 182 (19) ◽  
pp. 5615-5619 ◽  
Author(s):  
Jörg Sauer ◽  
Ulrike Dirmeier ◽  
Karl Forchhammer
Keyword(s):  
Glutamine Synthetase ◽  
Transcriptional Start Site ◽  
Binding Motif ◽  
Class Iii ◽  
Wild Type ◽  
Cloning And Sequencing ◽  
Gene Encoding ◽  
Low Concentrations ◽  
Synechococcus Strain ◽  
Pcc 7942

ABSTRACT We report the cloning and sequencing of the glnN gene encoding a class III glutamine synthetase from the cyanobacteriumSynechococcus strain PCC 7942. Mapping of the transcriptional start site revealed a DNA sequence in the promoter region that resembles an imperfect NtcA binding motif. Expression ofglnN is impaired in NtcA- and PII-deficient mutants. The only parameter which was negatively affected in theglnN mutant compared to the wild type was the recovery rate of prolonged nitrogen-starved cells with low concentrations of combined nitrogen.

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