Las proteínas DING, una familia con intrigantes funciones celulares

La familia de las proteínas DING recibe este nombre porque en especies filogenéticamente distantes, dichos aminoácidos están altamente conservados en el extremo N-terminal. Sus integrantes tienen un peso molecular ~40 kDa, están relacionadas con el metabolismo del fosfato, son secretadas y en su mayoría poseen actividad enzimática de fosfatasa. Inicialmente se creyó que las proteínas DING eran exclusivas de Pseudomonas sp., pero ahora se sabe que están distribuidas en los diferentes reinos biológicos. El descubrimiento de esta familia se fundamentó en la secuenciación de aminoácidos debido a que, con excepción de Pseudomonas fluorescens, P. aeruginosa y algunos otros procariontes, los genes que las codifican no han sido encontrados en las bases de genes de los eucariontes cuyos genomas han sido ya secuenciados. Las proteínas DING tienen funciones biológicas controversiales y por ello están siendo objeto de intensa investigación. En células animales se les ha asociado con la aparición de enfermedades como el cáncer de mama y la caquexia, pero también con la protección contra la arterioesclerosis y la litiasis. En vegetales, algunas proteínas DING muestran propiedades citotóxicas sobre células tumorales o de inhibición de la replicación del virus VIH-1. La evidencia biológica muestra que el mecanismo de acción de las proteínas DING puede ser variado y el resultado contrastante. Dada la potencial aplicación terapéutica de estas proteínas, en esta revisión se describen los hallazgos que se han realizando en esta familia debido a que previamente a su aplicación es necesario entender los mecanismos que regulan sus funciones. Abstract The DING family of proteins called because in phylogenetically distant species, these amino acids are highly conserved in the N- terminal. The members have a molecular weight of ~40 kDa, are related to phosphate metabolism, are secreted and have mostly phosphatase enzymatic activity. Initially it was believed that DING proteins were unique to Pseudomonas sp., but is now known they are distributed in different biological kingdoms. The discovery of this family was based on the sequencing of amino acids because, with the exception of Pseudomonas fluorescens, P. aeruginosa and some other prokaryotes, the genes that encode them have not been found on the basis of genes of eukaryotes whose genomes have already been sequenced. The DING proteins have controversial biological functions and are therefore the subject of intense research. In animal cells they have been associated with the occurrence of diseases such as breast cancer and cachexia, but also to protection against atherosclerosis and gallstones. In plants, DING proteins exhibit some cytotoxic properties on tumor cells or on inhibiting the replication of HIV-1 virus. Biological evidence shows that the mechanism of action of the DING proteins can be varied and with contrasting results. Given the potential therapeutic application of these proteins, in this review, we described the findings that have been made in this family, since before its exploitation it is necessary to understand the mechanisms that regulate their functions. Keywords: Hypericum perforatum; Pseudomonas sp., DING proteins, anticancer drugs

Protein Profiling of Psittacanthus calyculatus during Mesquite Infection

Psittacanthus calyculatus is a hemiparasite mistletoe that represents an ecological problem due to the impacts caused to various tree species of ecological and commercial interest. Although the life cycle for the Psittacanthus genus is well established in the literature, the development stages and molecular mechanism implicated in P. calyculatus host infection are poorly understood. In this study, we used a manageable infestation of P. laevigata with P. calyculatus to clearly trace the infection, which allowed us to describe five phenological infective stages of mistletoe on host tree branches: mature seed (T1), holdfast formation (T2), haustorium activation (T3), haustorium penetration (T4), and haustorium connection (T5) with the host tree. Proteomic analyses revealed proteins with a different accumulation and cellular processes in infective stages. Activities of the cell wall-degrading enzymes cellulase and β-1,4-glucosidase were primarily active in haustorium development (T3), while xylanase, endo-glucanase, and peptidase were highly active in the haustorium penetration (T4) and xylem connection (T5). Patterns of auxins and cytokinin showed spatial concentrations in infective stages and moreover were involved in haustorium development. These results are the first evidence of proteins, cell wall-degrading enzymes, and phytohormones that are involved in early infection for the Psittacanthus genus, and thus represent a general infection mechanism for other mistletoe species. These results could help to understand the molecular dialogue in the establishment of P. calyculatus parasitism

Auxin-Cytokinin Cross Talk in Somatic Embryogenesis of <i>Coffea canephora</i>

Cytokinins (CK) are plant growth regulators involved in multiple physiological processes in plants. One less studied aspect is CK homeostasis (HM). The primary genes related to HM are involved in biosynthesis (IPT), degradation (CKX), and signaling (ARR). This paper demonstrates the effect of auxin (Aux) and CK and their cross talk in a Coffea canephora embryogenic system. The transcriptome and RT-qPCR suggest that Aux in pre-treatment represses biosynthesis, degradation, and signal CK genes. However, in the induction, there is an increase of genes implicated in the CK perception/signal, indicating perhaps, as in other species, Aux is repressing CK, and CK are inducing per se genes involved in its HM. This is reflected in the endogenous concentration of CK; pharmacology experiments helped study the effect of each plant growth regulator in our SE system. We conclude that the Aux–CK balance is crucial to directing somatic embryogenesis in C. canephora

Metabolic Responses of the Microalga <i>Neochloris oleoabundans</i> to Extracellular Self- and Nonself-DNA

Stressed organisms identify intracellular molecules released from damaged cells due to trauma or pathogen infection as components of the innate immune response. These molecules called DAMPs (Damage-Associated Molecular Patterns) are extracellular ATP, sugars, and extracellular DNA, among others. Animals and plants can recognize their own DNA applied externally (self-exDNA) as a DAMP with a high degree of specificity. However, little is known about the microalgae responses to damage when exposed to DAMPs and specifically to self-exDNAs. Here we compared the response of the oilseed microalgae Neochloris oleoabundans to self-exDNA, with the stress responses elicited by nonself-exDNA, methyl jasmonate (MeJA) and sodium bicarbonate (NaHCO3). We analyzed the peroxidase enzyme activity related to the production of reactive oxygen species (ROS), as well as the production of polyphenols, lipids, triacylglycerols, and phytohormones. After 5 min of addition, self-exDNA induced peroxidase enzyme activity higher than the other elicitors. Polyphenols and lipids were increased by self-exDNA at 48 and 24 h, respectively. Triacylglycerols were increased with all elicitors from addition and up to 48 h, except with nonself-exDNA. Regarding phytohormones, self-exDNA and MeJA increased gibberellic acid, isopentenyladenine, and benzylaminopurine at 24 h. Results show that Neochloris oleoabundans have self-exDNA specific responses