Is there a Function for a Sex Pheromone Precursor?

AbstractFunctional coupling and comparative genomics analysis have been applied to study functional associations of orthologs of enterococcal cAD1 sex pheromone (P13268) known to be responsible for biofilm formation, conjugative plasmid transfer and spreading of bacterial antibiotics resistance. cAD1 peptide pheromone is released from the membrane lipoprotein with the peptide precursor encoded by a gene cad (tr|C2JQE7). Our analysis of genomic neighbourhood of cad and motifs of the encoded polypeptide and its orthologs suggests a close functional association between cAD1 and ApbE protein (Q82Z24), a FMN insertion and trafficking facilitator. The cad and apbE orthologs were coupled in the genomes and ApbE-specific motifs for FMN covalent attachment were identified in cad-encoded protein sequence and its orthologs. These findings suggest a potential role of FMN-based reductase function of the cAD1 lipoprotein precursor in its processing and release of the active sex pheromone peptide. They may lead to a new approach in prevention of antibiotic resistance spread via targeting sex pheromone processing chaperones or by suppression of the FMN availability and covalent binding. This methods can be also applied to a controlled evolution of bacterial pathogenicity in microbial fuel cells, as the findings suggest the crosstalk between bacterial pathogenicity and bacterial electro-activity.

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Site-Specific Protein Covalent Attachment to Nanotubes and Its Electronic Impact on Single Molecule Function

10.26434/chemrxiv.7798973.v1 ◽

2019 ◽

Author(s):

Adam Beachey ◽

Harley Worthy ◽

William David Jamieson ◽

Suzanne Thomas ◽

Benjamin Bowen ◽

...

Keyword(s):

Single Molecule ◽

Fluorescent Protein ◽

Functional Integration ◽

Attachment Site ◽

Covalent Attachment ◽

Great Promise ◽

Functional Coupling ◽

Phenyl Azide ◽

Electronic Impact ◽

Protein Attachment

<p>Functional integration of proteins with carbon-based nanomaterials such as nanotubes holds great promise in emerging electronic and optoelectronic applications. Control over protein attachment poses a major challenge for consistent and useful device fabrication, especially when utilizing single/few molecule properties. Here, we exploit genetically encoded phenyl azide photochemistry to define the direct covalent attachment of three different proteins, including the fluorescent protein GFP, to carbon nanotube side walls. Single molecule fluorescence revealed that on attachment to SWCNTs GFP’s fluorescence changed in terms of intensity and improved resistance to photobleaching; essentially GFP is fluorescent for much longer on attachment. The site of attachment proved important in terms of electronic impact on GFP function, with the attachment site furthest from the functional center having the larger effect on fluorescence. Our approach provides a versatile and general method for generating intimate protein-CNT hybrid bioconjugates. It can be potentially applied easily to any protein of choice; attachment position and thus interface characteristics with the CNT can easily be changed by simply placing the phenyl azide chemistry at different residues by gene mutagenesis. Thus, our approach will allow consistent construction and modulate functional coupling through changing the protein attachment position.</p>

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Non-Covalent Binding of Tripeptides-Containing Tryptophan to Polynucleotides and Photochemical Deamination of Modified Tyrosine to Quinone Methide Leading to Covalent Attachment

Molecules ◽

10.3390/molecules26144315 ◽

2021 ◽

Vol 26 (14) ◽

pp. 4315

Author(s):

Antonija Erben ◽

Igor Sviben ◽

Branka Mihaljević ◽

Ivo Piantanida ◽

Nikola Basarić

Keyword(s):

Quantum Yield ◽

Photophysical Properties ◽

Covalent Binding ◽

Quinone Methide ◽

Covalent Attachment ◽

Dna And Rna ◽

Pair Composition ◽

Aqueous Solvent ◽

Fluorometric Study ◽

Spectral Responses

A series of tripeptides TrpTrpPhe (1), TrpTrpTyr (2), and TrpTrpTyr[CH2N(CH3)2] (3) were synthesized, and their photophysical properties and non-covalent binding to polynucleotides were investigated. Fluorescent Trp residues (quantum yield in aqueous solvent ΦF = 0.03–0.06), allowed for the fluorometric study of non-covalent binding to DNA and RNA. Moreover, high and similar affinities of 2×HCl and 3×HCl to all studied double stranded (ds)-polynucleotides were found (logKa = 6.0–6.8). However, the fluorescence spectral responses were strongly dependent on base pair composition: the GC-containing polynucleotides efficiently quenched Trp emission, at variance to AT- or AU-polynucleotides, which induced bisignate response. Namely, addition of AT(U) polynucleotides at excess over studied peptide induced the quenching (attributed to aggregation in the grooves of polynucleotides), whereas at excess of DNA/RNA over peptide the fluorescence increase of Trp was observed. The thermal denaturation and circular dichroism (CD) experiments supported peptides binding within the grooves of polynucleotides. The photogenerated quinone methide (QM) reacts with nucleophiles giving adducts, as demonstrated by the photomethanolysis (quantum yield ΦR = 0.11–0.13). Furthermore, we have demonstrated photoalkylation of AT oligonucleotides by QM, at variance to previous reports describing the highest reactivity of QMs with the GC reach regions of polynucleotides. Our investigations show a proof of principle that QM precursor can be imbedded into a peptide and used as a photochemical switch to enable alkylation of polynucleotides, enabling further applications in chemistry and biology.

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