Biology subjects

Zaini, P. A.

Publications and source records attributed to Zaini, P. A..

5 recordsLinked to original sources

bioRxiv2025

Transcriptome profiling reveals differential expression of virulence genes in Xylella fastidiosa under nutrient-rich and xylem-like conditions

Xylella fastidiosa is a xylem-limited, insect-vectored pathogen. To capture the metabolic changes that underlie its adaptation to both nutrient-rich and xylem-like environments, we performed transcriptome analyses on two reference strains, Temecula1 and 9a5c, sampled at early and late exponential phases in a complex laboratory medium (PWG) and a defined, xylem-mimicking medium (PIM6). Across eight conditions (24 transcriptomes), over 90% of annotated coding sequences were expressed, although 40-80% of transcripts exhibited low abundance (TPM < 100). In contrast, a core set of highly abundant transcripts was seen in both strains and media, including the non-coding RNAs 6S and RNase P, as well as multiple colicin- and microcin-like toxins, proteases, lipases, and stress-response factors. Comprehensive pathway reconstruction confirmed the activity of all essential metabolic pathways, while revealing conditional enrichment of stress-related and defense modules under nutrient limitation. We annotated 5' and 3' untranslated regions for thousands of transcripts and defined over 900 operons across both genomes. Differential expression analysis demonstrated that PIM6 medium confers a far greater transcriptional reprogramming between early and late phases than PWG. Strain-to-strain comparisons revealed that up to 12.6% of orthologous genes were differentially regulated, emphasizing divergent regulatory networks even under identical growth conditions. This multi-dimensional transcriptome atlas not only refines X. fastidiosa genome annotation but also pinpoints candidate regulators, non-coding RNAs, and operon variants for functional validation. By illuminating the dynamic gene expression landscapes that enable xylem colonization and environmental resilience, our study lays a foundation for targeted disruption of key pathways in this important plant pathogen.

genetics↗

bioRxiv2025

Expression and Characterization of SARS-CoV-2 Spike Protein in Thermothelomyces heterothallica C1

The COVID-19 pandemic demonstrated a pressing need for rapid, adaptive, and scalable manufacturing of vaccines and reagents. With the transition into an endemic disease and rising threats of other emerging pandemics, production of these biologicals requires a stable and sustainable supply chain and accessible distribution methods. In this study, we demonstrate the strength of an engineered filamentous fungal platform, Thermothelomyces heterothallica C1, for high volumetric productivity of the full-length spike glycoprotein. Spike protein produced in this system is highly thermostable and immunization of mice with spike made in C1 or mammalian platforms resulted in a similar humoral response. Additionally, it was shown that the native N-glycan profile can be redecorated with complex sialylated structures, if necessary, resulting in a more human-like glycan profile, without impacting binding characteristics as shown experimentally and in simulations. Through extensive physicochemical analysis, the C1 produced spike performs similarly to spike proteins produced in other commercially available systems. The data presented is evidence that C1 can be a strong platform for production of complex glycosylated recombinant proteins such as subunit antigen vaccines.

bioengineering↗

bioRxiv2021

Comparative genomics of Xylella fastidiosa suggests determinants of host-specificity and expands its mobile genetic elements repertoire

The Gram-negative bacterium Xylella fastidiosa colonizes plant xylem vessels and is obligately vectored by xylem sap-feeding hemipteran insects. X. fastidiosa causes diseases in many plant species but in a variety of its plant hosts this bacterium behaves as a commensal endophyte. Originally confined to the Americas, infecting mainly grapevine, citrus and coffee plants, X. fastidiosa has spread to several plant species in Europe, causing devastating crop diseases. Although many pathogenicity and virulence factors have been identified in X. fastidiosa which enable the bacterium to successfully establish in the xylem tissue, the mechanisms by which distinct X. fastidiosa strains colonize and cause disease in specific plant hosts have not been fully elucidated. Here we present comparative analyses of 94 publicly available whole-genome sequences of X. fastidiosa strains with the goal of providing insights into plant host specificity determinants for this phytopathogen as well as of expanding the knowledge of its mobile genetic elements (MGE) content, mainly prophages. Our results revealed a pangenome of 4,549 protein coding sequences (CDSs) which is still open. The core- and accessory genomes comprise 954 and 2,219 CDSs, respectively. Phylogenetic tree construction using all core genome CDSs grouped the strains in three major clades of subspecies fastidiosa, multiplex and pauca, with subclades related to the strains sequence type (ST) obtained from multi-locus sequence typing (MLST). The geographic region where the strains were collected showed stronger association with the clades of X. fastidiosa strains rather than the plant species from which they were isolated. Among the CDS related to virulence and pathogenicity found in the core genome, those related to lipopolysaccharide (LPS) synthesis and trimeric autotransporter adhesins (TAA) are somewhat related with the plant host of a given strain according to phylogenetic inference. The X. fastidiosa accessory genome is represented by an abundant and heterogeneous mobilome, which includes a diversity of prophage regions. In summary, the genome comparisons reported here will enable a better understanding of the diversity of phylogenetically close genomes and warrant further investigation of LPS and TAAs as potential X. fastidiosa host-specificity determinants. Impact statementThe bacterium Xylella fastidiosa is a pathogen that infects many plant species and has caused devastating diseases in grapevine, citrus, coffee, and olive plants. This phytopathogen X. fastidiosa is original from the Americas and has emerged in Europe where it is causing severe economic losses for olive producers, mainly in Italy. Although many pathogenicity and virulence factors have been identified in X. fastidiosa, which enable this bacterium to successfully establish in the xylem vessels network, the mechanisms by which distinct X. fastidiosa strains colonize and cause disease in the different plant host species have not been fully elucidated. The comparative analyses of 94 whole-genome sequences from X. fastidiosa strains from diverse hosts and geographic regions provide insights into host specificity determinants for this phytopathogen as well as expand the knowledge of its mobile genetic elements (MGE) content, mainly prophages. Our results contribute for a better understanding of the diversity of phylogenetically close genomes and warrant further experimental investigation of lipopolysaccharide and trimeric autotransporter adhesins as potential host-specificity determinants for X. fastidiosa. Data summaryAll genomic sequences were accessed from publicly available GenBank RefSeq database at NCBI (National Center for Biotechnology Information). A full listing of NCBI accession numbers for X. fastidiosa strains described in this paper is available in Table S1 (available in the online version of this article).

genomics↗

bioRxiv2020

Deep learning neural network prediction method improves proteome profiling of vascular sap of grapevines during Pierce's disease development

Plant secretome studies have shown the importance of plant defense proteins in the vascular system against pathogens. Studies on Pierces disease of grapevines caused by the xylem-limited bacteria Xylella fastidiosa (Xf) have detected proteins and pathways associated to its pathobiology. Despite the biological importance of the secreted proteins in the extracellular space to plant survival and development, proteome studies are scarce due to technical and technological challenges. Deep learning neural network prediction methods can provide powerful tools for improving proteome profiling by data-independent acquisition (DIA). We aimed to explore the potential of this strategy by combining it with in silico spectral library prediction tool, Prosit, to analyze the proteome of vascular leaf sap of grapevines with Pierces disease. The results demonstrate that the combination of DIA and Prosit increased the total number of identified proteins from 145 to 360 for grapevines and 18 to 90 for Xf. The new proteins increased the range of molecular weight, assisted on the identification of more exclusive peptides per protein, and increased the identification of low abundance proteins. These increases allowed the identification of new functional pathways associated with cellular responses to oxidative stress to be further investigated.

genomics↗

bioRxiv2019

High-quality chromosome-scale assembly of the walnut (Juglans regia L) reference genome

The release of the first reference genome of walnut (Juglans regia L.) enabled many achievements in the characterization of walnut genetic and functional variation. However, it is highly fragmented, preventing the integration of genetic, transcriptomic, and proteomic information to fully elucidate walnut biological processes. Here we report the new chromosome-scale assembly of the walnut reference genome (Chandler v2.0) obtained by combining Oxford Nanopore long-read sequencing with chromosome conformation capture (Hi-C) technology. Relative to the previous reference genome, the new assembly features an 84.4-fold increase in N50 size, and the full sequence of all 16 chromosomal pseudomolecules, nine of which present telomere sequences at both ends. Using full-length transcripts from single-molecule real-time sequencing, we predicted 40,491 gene models, with a mean gene length higher than the previous gene annotations. Most of the new protein-coding genes (90%) are full-length, which represents a significant improvement compared to Chandler v1.0 (only 48%). We then tested the potential impact of the new chromosome-level genome on different areas of walnut research. By studying the proteome changes occurring during catkin development, we observed that the virtual proteome obtained from Chandler v2.0 presents fewer artifacts than the previous reference genome, enabling the identification of a new potential pollen allergen in walnut. Also, the new chromosome-scale genome facilitates in-depth studies of intraspecies genetic diversity by revealing previously undetected autozygous regions in Chandler, likely resulting from inbreeding, and 195 genomic regions highly differentiated between Western and Eastern walnut cultivars. Overall, Chandler v2.0 is a valuable resource to understand and explore walnut biology better.

genomics↗