Validação lateral em relações quantitativas entre estrutura e atividade farmacológica, QSAR

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Translated abstract

The comparative QSAR is a tool for validating any statistical model that seems to be reasonable in describing an interaction between a bioactive new chemical entity, BIONCE, and the biological system. In order to deeper the understanding of the relationships and the meaning of parameters within the model it is necessary some kind of lateral validation. This validation can be accomplished by chemical procedures using physicochemical organic reactions and by means of biological systems. In this paper we review some of such comparisons and also present a lateral validation between the same set of antimicrobial hydrazides acting against Saccharomyces cerevisiae yeast and Escherichia coli bacterium cells. QSARs are presented to shed light in this important way of stating that the QSAR model is not the endpoint, but the beginning.

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Most cited references 70

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FlhF is required for swimming and swarming in Pseudomonas aeruginosa.

Thomas Murray, Barbara I. Kazmierczak (2006)

FlhF is a signal recognition particle-like protein present in monotrichous bacteria. The loss of FlhF in various bacteria results in decreased transcription of class II, III, or IV flagellar genes, leads to diminished or absent motility, and results in the assembly of flagella at nonpolar locations on the cell surface. In this work, we demonstrate that the loss of FlhF results in defective swimming and swarming motility of Pseudomonas aeruginosa. The FlhF protein localizes to the flagellar pole; in the absence of FlhF, flagellar assembly occurs but is no longer restricted to the pole. DeltaflhF bacteria swim at lower velocities than wild-type bacteria in liquid media and can no longer swarm when assayed under standard swarming conditions (0.5% agar). However, DeltaflhF bacteria regain swarming behavior when plated on 0.3% agar. DeltaflhF organisms show decreased transcription and expression of flagellin (FliC) both in liquid media and on swarming plates compared to wild-type bacteria. However, changes in flagellin expression do not explain the different motility patterns observed for DeltaflhF bacteria. Instead, the aberrant placement of flagella in DeltaflhF bacteria may reduce their ability to move this rod-shaped organism effectively.

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Aerobactin biosynthesis and transport genes of plasmid ColV-K30 in Escherichia coli K-12.

V. Heras Cañas, A Bindereif, Torsten Neilands … (1986)

The iron-regulated aerobactin operon, about 8 kilobase pairs in size, of the Escherichia coli plasmid ColV-K30 was shown by deletion and subcloning analyses to consist of at least five genes for synthesis (iuc, iron uptake chelate) and transport (iut, iron uptake transport) of the siderophore. The gene order iucABCD iutA was established. The genes were mapped within restriction nuclease fragments of a cloned 16.3-kilobase-pair HindIII fragment. Stepwise deletion and subsequent minicell analysis of the resulting plasmids allowed assignment of four of the five genes to polypeptides of molecular masses 63,000, 33,000 53,000, and 74,000 daltons, respectively. The 74-kilodalton protein, the product of gene iutA, is the outer membrane receptor for ferric aerobactin, whereas the remaining three proteins are involved in biosynthesis of aerobactin. The 33-kilodalton protein, the product of gene iucB, was identified as N epsilon-hydroxylysine:acetyl coenzyme A N epsilon-transacetylase (acetylase) by comparison of enzyme activity in extracts from various deletion mutants. The 53-kilodalton protein, the product of gene iucD, is required for oxygenation of lysine. The 63-kilodalton protein, the product of gene iucA, is assigned to the first step of the aerobactin synthetase reaction. The product of gene iucC, so far unidentified, performs the second and final step in this reaction. This is based on the chemical characterization of two precursor hydroxamic acids (N epsilon-acetyl-N epsilon-hydroxylysine and N alpha-citryl-N epsilon-acetyl-N epsilon-hydroxylysine) isolated from a strain carrying a 0.3-kilobase-pair deletion in the iucC gene. The results support the existence of a biosynthetic pathway in which aerobactin arises by oxygenation of lysine, acetylation of the N epsilon-hydroxy function, and condensation of 2 mol of the resulting aminohydroxamic acid with citric acid.

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Characterization of the Ustilago maydis sid2 gene, encoding a multidomain peptide synthetase in the ferrichrome biosynthetic gene cluster.

W Yuan, A Budde, I U S Leong … (2001)

Ustilago maydis, the causal agent of corn smut disease, acquires and transports ferric ion by producing the extracellular, cyclic peptide, hydroxamate siderophores ferrichrome and ferrichrome A. Ferrichrome biosynthesis likely proceeds by hydroxylation and acetylation of L-ornithine, and later steps likely involve covalently bound thioester intermediates on a multimodular, nonribosomal peptide synthetase. sid1 encodes L-ornithine N(5)-oxygenase, which catalyzes hydroxylation of L-ornithine, the first committed step of ferrichrome and ferrichrome A biosynthesis in U. maydis. In this report we characterize sid2, another biosynthetic gene in the pathway, by gene complementation, gene replacement, DNA sequence, and Northern hybridization analysis. Nucleotide sequencing has revealed that sid2 is located 3.7 kb upstream of sid1 and encodes an intronless polypeptide of 3,947 amino acids with three iterated modules of an approximate length of 1,000 amino acids each. Multiple motifs characteristic of the nonribosomal peptide synthetase protein family were identified in each module. A corresponding iron-regulated sid2 transcript of 11 kb was detected by Northern hybridization analysis. By contrast, constitutive accumulation of this large transcript was observed in a mutant carrying a disruption of urbs1, a zinc finger, GATA family transcription factor previously shown to regulate siderophore biosynthesis in Ustilago. Multiple GATA motifs are present in the intergenic region between sid1 and sid2, suggesting bidirectional transcription regulation by urbs1 of this pathway. Indeed, mutation of two of these motifs, known to be important to regulation of sid1, altered the differential regulation of sid2 by iron.

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Author and article information

Contributors

Maria Luiza C. Montanari: Role: ND

Carlos A. Montanari: Role: ND

Anderson C. Gaudio: Role: ND

Journal

Journal ID (publisher): qn

Title: Química Nova

Abbreviated Title: Quím. Nova

Publisher: Sociedade Brasileira de Química (São Paulo )

ISSN: 1678-7064

Publication date (Print): May 2002

Volume: 25

Issue: 2

Pages: 231-240

Affiliations

[1 ] Universidade Federal de Minas Gerais Brazil

[2 ] Universidade Federal do Espírito Santo Brazil

Article

Publisher ID: S0100-40422002000200011

DOI: 10.1590/S0100-40422002000200011

SO-VID: fc44c712-81f5-4f38-beab-63b274b00f63

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http://creativecommons.org/licenses/by/4.0/

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SciELO Brazil

Self URI (journal page): http://www.scielo.br/scielo.php?script=sci_serial&pid=0100-4042&lng=en

Validação lateral em relações quantitativas entre estrutura e atividade farmacológica, QSAR Translated title: Comparative QSAR of antimicrobial hydrazides

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Most cited references 70

FlhF is required for swimming and swarming in Pseudomonas aeruginosa.

Aerobactin biosynthesis and transport genes of plasmid ColV-K30 in Escherichia coli K-12.

Characterization of the Ustilago maydis sid2 gene, encoding a multidomain peptide synthetase in the ferrichrome biosynthetic gene cluster.

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