No abstract

A boron-dipyrromethene (BODIPY) derivative reactive towards amino groups of proteins (NHS-Ph-BODIPY) was synthesized. Spectroscopic and photophysical properties of amine-reactive NHS-Ph-BODIPY and its non-reactive precursor (COOH-Ph-BODIPY) in a number of organic solvents were investigated. Both fluorescent dyes were characterized by green absorption (521–532 nm) and fluorescence (538–552 nm) and medium molar absorption coefficients (46,500–118,500 M−1·cm−1) and fluorescence quantum yields (0.32 – 0.73). Solvent polarizability and dipolarity were found to play a crucial role in solvent effects on COOH-Ph-BODIPY and NHS-Ph-BODIPY absorption and emission bands maxima. Quantum-chemical calculations were used to show why solvent polarizability and dipolarity are important as well as to understand how the nature of the substituent affects spectroscopic properties of the fluorescent dyes. NHS-Ph-BODIPY was used for fluorescent labeling of a number of proteins. Conjugation of NHS-Ph-BODIPY with bovine serum albumin (BSA) resulted in bathochromic shifts of absorption and emission bands and noticeable fluorescence quenching (about 1.5 times). It was demonstrated that the sensitivity of BSA detection with NHS-Ph-BODIPY was up to eight times higher than with Coomassie brilliant blue while the sensitivity of PII-like protein PotN (PotN) detection with NHS-Ph-BODIPY and Coomassie brilliant blue was almost the same. On the basis of the molecular docking results, the most probable binding sites of NHS-Ph-BODIPY in BSA and PotN and the corresponding binding free energies were estimated.

Lactic acid bacteria (LAB) are Gram-positive, non-spore forming, facultative anaerobic or microaerophilic bacteria living in various nutrients-rich ecological niches and are widely used for dairy food and silage production as well as probiotics for the Human and animals. While bacteria can assimilate various nitrogen-containing compounds, the glutamine and ammonium are the most preferred nitrogen sources since they could be directly involved into the nitrogen metabolism of the cell. In bacterial cells, the glutamine can be synthetized from glutamate and ammonium ions by the metalloenzyme glutamine synthetase (GS). In contrast to other bacteria which generally have one gene encoding for the glutamine synthetase, two genes encoding proteins with 53% mutual identity and predicted glutamine synthetase activity were found in the genome of Lactobacillus hilgardii LMG 7934. One gene (glnA_2) is located in the glnRA operon with the transcriptional factor GlnR gene (glnR) similarly to GS genes from other bacteria. The second GS gene (glnA_1) is monocistronic. While the biosynthetic activity glutamine synthetases could be detected in L. hilgardii cells, which protein plays the major role is still unclear.

PII proteins are signal processor proteins that regulate the cellular metabolism of Bacteria, Archea and plant chloroplasts typically in response to the cellular nitrogen status. Here, we report the first biochemical characterization of a novel PII‐like protein PotN from Lentilactobacillus hilgardii. PotN is encoded in an operon together with the potABCD genes, encoding the ABC transporter for spermidine/putrescine. Like canonical PII proteins, the native PotN has a trimeric structure and competitively binds ATP and ADP, but it does not bind 2‐oxoglutarate. Immunoprecipitation and pull‐down experiments revealed that PotN is associated in vivo with the transcriptional regulator GlnR and the beta‐subunit of pyruvate/2‐oxoglutarate/acetoin dehydrogenase AcoB. Moreover, in vitro assays revealed that the ATPase domain of PotA also is able to interact with PotN. Interaction analyses demonstrated that PotN preferentially associates with PotA in the ADP state, whereas it binds to GlnR at elevated ATP levels. This suggests that PotN regulates the transport of polyamines and GlnR‐dependent gene expression in response to the energy availability for the cell.

Here we report the whole genome sequence of Lactobacillus fermentum HFD1 strain, the producer of antibacterial peptides. The genome consists of one circular chromosome with 2101878 bp in length and GC-content of 51.8%, and includes linear DNA with 5386 bp in length with 100% identity to bacteriophage phiX174. The analysis of the genome has revealed 2049 genes encoding for proteins including 867 proteins without known function and 70 genes encoding for RNAs (10 rRNAs, 59 tRNAs and 1 tmRNA). Putative genes responsible for the biosynthesis of 4 antimicrobial peptides were identified. The NCBI Bioproject has been deposited at NCBI under the accession number PRJNA615901 ( https://www.ncbi.nlm.nih.gov/bioproject/PRJNA615901/ ) and consist of full annotated genome and raw sequence data.