Lactococcus cell envelope proteases enable lactococcal growth in minimal growth media supplemented with high molecular weight proteins of plant and animal origin

Lactic acid bacteria (LAB) have evolved into fastidious microorganisms that require amino acids from environmental sources. Some LAB have cell envelope proteases (CEPs) that drive the proteolysis of high molecular weight proteins like casein in milk. CEP activity is typically studied using casein as the predominant substrate, even though CEPs can hydrolyze other protein sources. Plant protein hydrolysis by LAB has rarely been connected to the activity of specific CEPs. This study aims to show the activity of individual CEPs using LAB growth in a minimal growth medium supplemented with high molecular weight casein or potato proteins. Using Lactococcus cremoris MG1363 as isogenic background to express CEPs, we demonstrate that CEP activity is directly related to growth in the protein-supplemented minimal growth media. Proteolysis is analyzed based on the amino acid release, allowing a comparison of CEP activities and analysis of amino acid utilization by L. cremoris MG1363. This approach provides a basis to analyze CEP activity on plant-based protein substrates as casein alternatives and to compare activity of CEP homologs.

Comparative Structure Analysis of the Multi-Domain, Cell Envelope Proteases of Lactic Acid Bacteria

Lactic acid bacteria (LAB) have an extracellular proteolytic system that includes a multi-domain, cell envelope protease (CEP) with a subtilisin homologous protease domain. These CEPs have different proteolytic activities despite having similar protein sequences. Structural characterization has previously been limited to CEP homologs of dairy- and human-derived LAB strains, excluding CEPs of plant-derived LAB strains. CEP structures are a challenge to determine experimentally due to their large size and attachment to the cell envelope. This study aims to clarify the prevalence and structural diversity of CEPs by using the structure prediction software AlphaFold 2. Domain boundaries are clarified based on a comparative analysis of 21 three-dimensional structures, revealing novel domain architectures of CEP homologs that are not necessarily restricted to specific LAB species or ecological niches. The C-terminal flanking region of the protease domain is divided into fibronectin type-III-like domains with various structural traits. The analysis also emphasizes the existence of two distinct domains for cell envelope attachment that are preceded by an intrinsically disordered cell wall spanning domain. The domain variants and their combinations provide CEPs with different stability, proteolytic activity, and potentially adhesive properties, making CEPs targets for steering proteolytic activity with relevance for both food development and human health.

Impact of maternal mental health problems on perinatal outcomes for the infant

Background

Mounting evidence suggests that mental health problems in pregnant women may negatively affect the intra- and extrauterine health and development of the child. This is especially of concern as the prevalence of mental health problems in pregnant women is high and believed to be increasing. We set out to quantify the effect of maternal mental health status on the risk of adverse perinatal outcomes for the infant.

Methods

We undertook a nationwide register-based cohort study including children born alive in Denmark between 2000 and 2016. The exposed cohort was children born to mothers with mental health problems in the two years prior to childbirth that had been cared for in primary care settings only (Group 1, minor problems, n = 71 759) or had required psychiatric intervention (Group 2, moderate-severe problems, n = 41 099). All non-exposed children served as comparison group (n = 908 268). We calculated risk ratios (RRs) with 95% confidence intervals (CI) for each perinatal outcome of interest.

Results

Infants in Group 1 as well as Group 2 were at higher risk of neonatal death than infants born to unaffected mothers, although for Group 2 the trend was non-significant (Group 1: adjusted RR (aRR) 1.34, 95% CI 1.17-1.52; Group 2: aRR 1.11, 95% CI 0.94-1.32). Both exposure groups were furthermore at significantly increased risk of 5-minute Apgar scores <7 (Group 1: aRR 1.27, 95% CI 1.17-1.37; Group 2: aRR 1.52, 95% CI 0.94-1.32) and <4 (Group 1: aRR 1.26, 95% CI 1.10-1.44; Group 2: aRR 1.28, 95% CI 1.08-1.52) and of hospital admission in the neonatal period (Group 1: aRR 1.22, 95% CI 1.19-1.24; Group 2: 1.29, 95% CI 1.26-1.32), paralleled by a significantly higher risk of preterm birth and several neonatal morbidities.

Conclusions

Infants born to mothers with moderate-severe as well as minor mental health problems were at increased risk of multiple adverse perinatal outcomes, thus calling for effective preventive strategies to improve outcomes in both groups.

Evolutionary conservation of the intrinsic disorder-based Radical-Induced Cell Death1 hub interactome

Radical-Induced Cell Death1 (RCD1) functions as a cellular hub interacting with intrinsically disordered transcription factor regions, which lack a well-defined three-dimensional structure, to regulate plant stress. Here, we address the molecular evolution of the RCD1-interactome. Using bioinformatics, its history was traced back more than 480 million years to the emergence of land plants with the RCD1-binding short linear motif (SLiM) identified from mosses to flowering plants. SLiM variants were biophysically verified to be functional and to depend on the same RCD1 residues as the DREB2A transcription factor. Based on this, numerous additional members may be assigned to the RCD1-interactome. Conservation was further strengthened by similar intrinsic disorder profiles of the transcription factor homologs. The unique structural plasticity of the RCD1-interactome, with RCD1-binding induced α-helix formation in DREB2A, but not detectable in ANAC046 or ANAC013, is apparently conserved. Thermodynamic analysis also indicated conservation with interchangeability between Arabidopsis and soybean RCD1 and DREB2A, although with fine-tuned co-evolved binding interfaces. Interruption of conservation was observed, as moss DREB2 lacked the SLiM, likely reflecting differences in plant stress responses. This whole-interactome study uncovers principles of the evolution of SLiM:hub-interactions, such as conservation of α-helix propensities, which may be paradigmatic for disorder-based interactomes in eukaryotes.

Synthesis and enzymatic and inotropic activity of some new 8-substituted and 6,8-disubstituted derivatives of adenosine cyclic 3',5'-monophosphate

The synthesis of certain new 8-(arythio)- and 8-(alkylthio)-cAMP derivatives and N6-alkyl- and N6-dialkyl-8-(arylthio) and -8-(alkylthio) derivatives of cAMP is reported. On the basis of activation of protein kinase, several N6-alkyl-8-(benzylthio)-cAMP derivatives were selected for evaluation as inotropic agents using cat papillary muscle in vitro. Activity in these studies resulted in the selection of several analogues for in vivo studies in the anesthetized dogs. The best inotropic agent selected on the basis of in vivo studies was N6-butyl-8-(benzylthio)-cAMP (26), which exhibited an increase in blood-flow rate of 85% with no increase in heart rate. A large-scale synthesis of 26 from cAMP is reported via N1-alkylation, followed by a Dimroth rearrangement, reduction, bromination, and nucleophilic displacement via benzyl mercaptan. The N6-alkyl-8-substituted-cAMP derivatives represent a new class of potent inotropic agents. The direct mechanism of action of 26 suggests the possible utility of this cyclic nucleotide to treat clinical myocardial infarction by rapid intravenous infusion.

Synthesis and antiviral acticity of some phosphates of the broad-spectrum antiviral nucleoside, 1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide (ribavirin)

1-beta-D-Ribofuranosyl-1,2,4-triazole-3-carboxamide 5'-phosphate (2) was prepared and converted into the following derivatives: the 5'-phosphoramidate 3, the 5'-diphosphate 4, the 5'-triphosphate 5, and the cyclic 3',5'-phosphate 6. The cyclic 2',3'-phosphate 7 was prepared from the parent nucleoside, 1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide (1), and was opened to the 2'(3')-phosphate 8. These compounds were found to exhibit significant antiviral activity against several viruses in cell culture. Ribavirin 5'-phosphate (2) was shown to be effective when tested against lethal infections in mice caused by influenza A2, influenza B, and murine hepatitis viruses.

Interaction of "aza" and "deaza" analogs of adenosine cyclic 3', 5'-phosphate with some enzymes of adenosine cyclic 3', 5'-phosphate metabolism: evidence that the lone pair electrons of N-3 are involved in the binding of adenosine cyclic 3', 5'-phosphate to type II adenosine cyclic 3', 5'-phosphate-dependent protein kinase

Five hetercyclic analogs of adenosine cyclic 3',5'-phosphate (cyclic AMP) were examined for their ability (1) to stimulate type II cyclic AMP-dependent kinases from bovine brain, bovine heart, and rat liver; (2) to serve as substrates for "high Km" (Km for cyclic AMP = 0.13-0.43 mM) cyclic nucleotide phosphodiesterases from bovine heart, rabbit kidney, and rat liver; and (3) to inhibit the hydrolysis of cyclic AMP catalyzed by "low Km" (Km for cAMP = 0.32-1.5 muM) cyclic nucleotide phosphodiesterases from bovine brain, bovine heart, dog heart, rabbit liver, rat brain and rat liver. The analogs all had a purine ring system which had been modified by replacement of a ring carbon with nitrogen or vice versa to yield 2-aza-cAMP (7-amino-4-beta-D-ribofuranosylimidazo [4,5-d] -v-triazine cyclic 3',5'-phosphate); 8-aza-cAMP (7-amino-3-beta-D-ribofuranosyl-v-triazolo-[4,5-d]-pyrimidine cyclic 3',5'-phosphate); 1 deaza-cAMP (7-amino-3-beta-D-ribofuranosylimidazo [4,5-b[pyridine cyclic 3',5'-phosphate); 3-deaza-cAMP (4-amino-1-beta-D-ribofuranosylimidazo[4,5-c]pyridine cyclic 3',5'-phosphate) and 7-deaza-cAMP (7-amino-4-beta-D-ribofuranosylpyrrolo[2,3-d]pyrimidine cyclic 3',5'-phosphate).

Synthesis and enzymic activity of 8-acyl and 8-alkyl derivatives of guanosine 3, 5-cyclic phosphate

Several new 8-alkyl and 8-acyl derivatives of quanosie 3',5'-cyclic phosphate (cGMP) and inosine 3',5'-cyclic phosphate (cGMP) were prepared by direct alkylation or acylation of the parent cyclic nucleotide via free radicals generated in situ. These compounds have been examined for their ability to stimulate a cGMP-dependent protein kinase, and several of the cGMP derivatives were as active in this regard as cGMP. These compounds proved to be quite ineffective when tested for their ability to activate an adenosine 3',5'-cyclic phosphate (cAMP) dependent protein kinase. In addition, these 8-substituted cGMP derivatives are not substrates for a phosphodiesterase preparation from rabbit kidney, but do show inhibition of the hydrolysis of cAMP by crude phosphodiesterase preparations from rabbit lung and beef heart.