Biology subjects

Hong, Q.

Publications and source records attributed to Hong, Q..

10 recordsLinked to original sources

bioRxiv2026

Fast and reliable association discovery in large-scale microbiome studies and meta-analyses using PALM

Identifying microbial features associated with various covariates is a long-standing goal in microbiome research. Modern association studies incorporate an ever-increasing number of microbial features, covariates, and datasets from diverse cohorts. However, the complexity of microbiome data challenges analysis, often leading to poor replication of findings. We introduce PALM, a quasi-Poisson regression framework that enables fast and reliable association discovery in large-scale studies and meta-analyses. Extensive, realistic simulations demonstrate PALMs advantages in controlling false discovery rates, boosting power, improving computational efficiency, and preserving cross-study homogeneity of association effects. Three real-world applications at different scales illustrate PALMs utility, underscoring its potential to advance microbiome research.

microbiology↗

bioRxiv2025

Widespread distribution of the BpfA-carrying bacteria involved in the bisphenol F degradation in Pseudomonadota and Actinomycetota

The global use of bisphenol F (BPF) has led to widespread environmental contamination, posing significant threats to ecosystems and human health. However, the genes involved in BPF degradation remained unknown. In this study, a novel oxidase gene, bpfA, was obtained from strain Microbacterium sp. F2 through a four-step purification strategy. BpfA is classified as a member of the 4-phenol oxidizing (4PO) subfamily and contains a conserved FAD-binding domain (Asp152 and His393) as well as a Tyr-Tyr-Arg triad (Tyr93, Tyr474, Arg475). BpfA catalyzes the conversion of BPF to 4,4-dihydroxydibenzophenone (DHBP) through a series of three consecutive reactions. In addition, BpfA exhibits catalytic activity towards 4-alkylphenols, such as vanillyl alcohol (VA), 4-n-propylguaiacol (4PG), and 4-(methoxymethyl)phenol (4MOP). BpfA homologs are widely distributed in the environment, particularly in soil. Bioinformatics-based taxonomic profiling revealed that BpfA homologs are widely distributed in metagenomes from cultivated land and forests, mainly belonging to Pseudomonadota and Actinomycetota. This study enhances our understanding of the microbial degradation mechanism of BPF, elucidates the catalytic function of the novel oxidase gene bpfA and its distribution pattern in the environment, and provides important insights into the evolutionary origin of BPF degradation genes and the targeted mining of environmental microbial resources.

microbiology↗

bioRxiv2024

Development of immobilized antibody-based affinity grid strategy and application in on-grid purification of target proteins for high-resolution cryo-EM

In cryo-electron microscopy (cryo-EM), sample preparation, especially for rare or fragile macromolecular assemblies and those suffering from air-water interface denaturation and particle orientation distribution problems, is a major bottleneck. Here, we developed and characterized an immobilized antibody-based affinity grid (IAAG) strategy based on the high-affinity PA tag/NZ-1 antibody epitope tag system. We used Pyr-NHS as a linker to immobilize NZ-1 Fab on the graphene oxide or carbon covered grid surface. We showed that the IAAG grid can enrich the PA-tagged target proteins, and overcome preferred orientation problems. Furthermore, we demonstrated that our IAAG strategy can be utilized for on-grid purification of low-abundance target complexes from cell lysates and enables atomic resolution cryo-EM. This approach greatly streamlines the purification process, reduces the need for large quantities of biological samples, and addresses common challenges encountered in cryo-EM sample preparation. Collectively, our IAAG strategy provides an efficient and robust means for combined sample purification and vitrification feasible for high-resolution cryo-EM. This approach also has the potential for broader applicability in cryo-EM and cryo-ET.

molecular biology↗

bioRxiv2023

High-resolution structure of mouse radial spoke and its in-situ structure in ependymal cilia revealed by cryo-EM and cryo-ET

Radial spokes (RS) transmit mechanochemical signals between the central pair (CP) and axonemal dynein arms to coordinate ciliary motility. However, the high-resolution structure of mammalian RS remains missing. Here, we present the high-resolution cryo-EM structure of mouse RS head-neck complex in both monomer and dimer forms and reveal the intrinsic dynamics of the dimer. We also map the genetic mutations related to primary ciliary dyskinesia and asthenospermia on the head-neck complex. Moreover, we present the unprecedented cryo-ET and sub-tomogram averaging map of mouse ependymal cilia, whose beating creates unidirectional cerebrospinal fluid flow, and build the models for RS1-3, IDAs, and N-DRC. Strikingly, our cryo-ET map reveals the lack of IDA-b/c/e and the absence of tektin filaments within the A-tubule of doublet microtubules in ependymal cilia compared with mammalian respiratory cilia and sperm flagella. This tissue-specific feature may represent an evolutionary choice driven by the functional requirements on ependymal cilia. Our findings reveal the RS head-neck assembly mechanism, shed light on the coordinated rigid and elastic RS-CP interaction modes beneficial for the regulation of asymmetric ciliary beating, and also facilitate understandings on the etiology of ciliary dyskinesia-related ciliopathies.

biophysics↗

bioRxiv2022

Molecular basis of SARS-CoV-2 Omicron variant receptor engagement and antibody evasion and neutralization

The SARS-CoV-2 Omicron variant exhibits striking immune evasion and is spreading globally at an unprecedented speed. Understanding the underlying structural basis of the high transmissibility and greatly enhanced immune evasion of Omicron is of high importance. Here through cryo-EM analysis, we present both the closed and open states of the Omicron spike, which appear more compact than the counterparts of the G614 strain, potentially related to the Omicron substitution induced enhanced protomer-protomer and S1-S2 interactions. The closed state showing dominant population may indicate a conformational masking mechanism of immune evasion for Omicron spike. Moreover, we capture two states for the Omicron S/ACE2 complex with S binding one or two ACE2s, revealing that the substitutions on the Omicron RBM result in new salt bridges/H-bonds and more favorable electrostatic surface properties, together strengthened interaction with ACE2, in line with the higher ACE2 affinity of the Omicron relative to the G614 strain. Furthermore, we determine cryo-EM structures of the Omicron S/S3H3 Fab, an antibody able to cross-neutralize major variants of concern including Omicron, elucidating the structural basis for S3H3-mediated broad-spectrum neutralization. Our findings shed new lights on the high transmissibility and immune evasion of the Omicron variant and may also inform design of broadly effective vaccines against emerging variants.

biochemistry↗

bioRxiv2020

Conformational dynamics of SARS-CoV-2 trimeric spike glycoprotein in complex with receptor ACE2 revealed by cryo-EM

The recent outbreaks of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its rapid international spread pose a global health emergency. The trimeric spike (S) glycoprotein interacts with its receptor human ACE2 to mediate viral entry into host-cells. Here we present cryo-EM structures of an uncharacterized tightly closed SARS-CoV-2 S-trimer and the ACE2-bound-S-trimer at 2.7-Å and 3.8-Å-resolution, respectively. The tightly closed S-trimer with inactivated fusion peptide may represent the ground prefusion state. ACE2 binding to the up receptor-binding domain (RBD) within S-trimer triggers continuous swing-motions of ACE2-RBD, resulting in conformational dynamics of S1 subunits. Noteworthy, SARS-CoV-2 S-trimer appears much more sensitive to ACE2-receptor than SARS-CoV S-trimer in terms of receptor-triggered transformation from the closed prefusion state to the fusion-prone open state, potentially contributing to the superior infectivity of SARS-CoV-2. We defined the RBD T470-T478 loop and residue Y505 as viral determinants for specific recognition of SARS-CoV-2 RBD by ACE2, and provided structural basis of the spike D614G-mutation induced enhanced infectivity. Our findings offer a thorough picture on the mechanism of ACE2-induced conformational transitions of S-trimer from ground prefusion state towards postfusion state, thereby providing important information for development of vaccines and therapeutics aimed to block receptor binding.Competing Interest StatementThe authors have declared no competing interest.View Full Text

molecular biology↗

bioRxiv2020

Role of RgsA in oxidative stress resistance in Pseudomonas aeruginosa

Pseudomonas aeruginosa is an extremely common opportunistic pathogen in clinical practice. Patients with metabolic disorders, hematologic diseases, malignancies, who have undergone surgery or who have received certain treatments are susceptible to this bacterium. In addition, P. aeruginosa is a multidrug-resistant that tends to form biofilms and is refractory to treatment. Small regulatory RNAs are RNA molecules that are 40-500 nucleotides long, possess regulatory function, are ubiquitous in bacteria, and are also known as small RNA (sRNA). sRNAs play important regulatory roles in various vital life processes in diverse bacteria and their quantity and diversity of regulatory functions exceeds that of proteins. In this study, we showed that deletion of the sRNA RgsA decreases the growth rate and ability to resist different concentrations and durations of peroxide in P. aeruginosa. These decreases occur not only in the planktonic state, but also in the biofilm state. Finally, protein mass spectrometry was employed to understand changes in the entire protein spectrum. The results presented herein provide a description of the role of RgsA in the life activities of P. aeruginosa at the molecular, phenotypic, and protein levels.

microbiology↗

bioRxiv2019

Identification and characterization of a novel pic gene cluster responsible for picolinic acid degradation in Alcaligenes faecalis JQ135

Picolinic acid (PA) is a natural toxic pyridine derivative. Microorganisms can degrade and utilize PA for growth. However, the full metabolic pathway and its physiological and genetic foundation remain unknown. In this study, we identified the pic gene cluster responsible for the complete degradation of PA from Alcaligenes faecalis JQ135. PA was initially 6-hydroxylated into 6-hydroxypicolinic acid (6HPA) by PA dehydrogenase (PicA). 6HPA was then 3-hydroxylated by a four-component 6HPA monooxygenase (PicB) to form 3,6-dihydroxypicolinic acid (3,6DHPA), which was then converted into 2,5-dihydroxypyridine (2,5DHP) by a decarboxylase (PicC). The 2,5DHP was further degraded into fumaric acid, through PicD (2,5DHP dioxygenase), PicE (N-formylmaleamic acid deformylase), PicF (maleamic acid amidohydrolase), and PicG (maleic acid isomerase). Homologous pic gene clusters with diverse organizations were found to be widely distributed in -, {beta}-, and{gamma} -Proteobacteria. Our findings provide new insights into the microbial metabolism of environmental toxic pyridine derivatives. ImportancePicolinic acid is a common metabolite of L-tryptophan and some aromatic compounds and is an important intermediate of industrial concern. Although the microbial degradation/detoxification of picolinic acid has been studied for over 50 years, the underlying molecular mechanisms are still unknown. Here, we show the pic gene cluster responsible for the complete degradation of picolinic acid into the tricarboxylic acid cycle. This gene cluster was found to be widespread in other -, {beta}-, and{gamma} -Proteobacteria. These findings provide new perspective for understanding the mechanisms of picolinic acid biodegradation in bacteria.

microbiology↗

bioRxiv2018

Novel 3,6-Dihydroxypicolinic Acid Decarboxylase Mediated Picolinic Acid Catabolism in Alcaligenes faecalis JQ135

Alcaligenesfaecalis strain JQ135 utilizes picolinic acid (PA) as sole carbon and nitrogen source for growth. In this study, we screened a 6-hydroxypicolinic acid (6HPA) degradation-deficient mutant through random transposon mutagenesis. The mutant hydroxylated 6HPA into an intermediate, identified as 3,6-dihydroxypicolinic acid (3,6DHPA) with no further degradation. A novel decarboxylase PicC was identified that was found to be responsible for the decarboxylation of 3,6DHPA to 2.5-dihydroxypyridine. Although, PicC belonged to amidohydrolase_2 family, it shows low similarity (<45%) when compared to other reported amidohydrolase_2 family decarboxylases. Moreover, PicC was found to form a monophyletic group in the phylogenetic tree constructed using PicC and related proteins. Further, the genetic deletion and complementation results demonstrated that picC was essential for PA degradation. The PicC was Zn2+-dependent non-oxidative decarboxylase that can specifically catalyze the irreversible decarboxylation of 3,6DHPA to 2.5-dihydroxypyridine. The Km and kcat towards 3,6DHPA were observed to be 13.44 M and 4.77 s-1, respectively. Site-directed mutagenesis showed that His163 and His216 were essential for PicC activity.\n\nImportancePicolinic acid is a natural toxic pyridine derived from L-tryptophan metabolism and some aromatic compounds in mammalian and microbial cells. Microorganisms can degrade and utilize picolinic acid for their growth, and thus, a microbial degradation pathway of picolinic acid has been proposed. Picolinic acid is converted into 6-hydroxypicolinic acid, 3,6-dihydroxypicolinic acid, and 2,5-dihydroxypyridine in turn. However, there was no physiological and genetic validation for this pathway. This study demonstrated that 3,6DHPA was an intermediate in PA catabolism process and further identified and characterized a novel amidohydrolase_2 family decarboxylase PicC. It was also shown that PicC could catalyze the decarboxylation process of 3,6-dihydroxypicolinic acid into 2,5-dihydroxypyridine. This study provides a basis for understanding PA degradation pathway and the underlying molecular mechanism.

microbiology↗

bioRxiv2017

The Novel Monocomponent FAD-dependent Monooxygenase HpaM Catalyzes the 2-Decarboxylative Hydroxylation of 5-Hydroxypicolinic Acid in Alcaligenes faecalis JQ135

5-hydroxypicolinic acid (5HPA) is a natural pyridine derivative that can be microbially degraded. However, the physiological, biochemical, and genetic foundation of the microbial catabolism of 5HPA remains unknown. In this study, a gene cluster hpa (which is involved in degradation of 5HPA in Alcaligenes faecalis JQ135) was cloned and HpaM was identified as a novel monocomponent FAD-dependent monooxygenase. HpaM shared a sequence only 31% similarity with the most related protein 6-hydroxynicotinate 3-monooxygenase (NicC) of Pseudomonas putida KT2440. hpaM was heterologously expressed in E. coli BL21(DE3), and the recombinant HpaM was purified via Ni-affinity chromatography. HpaM catalyzed the 2-decarboxylative hydroxylation of 5-HPA, thus generating 2,5-dihydroxypyridine (2,5-DPH). Monooxygenase activity was only detected in the presence of FAD and NADH, but not of FMN and NADPH. The apparent Km values of HpaM toward 5HPA and NADH were 45.4 and 37.8 , respectively. Results of gene deletion and complementation showed that hpaM was essential for 5HPA degradation in Alcaligenes faecalis JQ135.\n\nImportancePyridine derivatives are ubiquitous in nature and important chemical materials that are currently widely used in agriculture, pharmaceutical, and chemical industries. Thus, the microbial degradation and transformation mechanisms of pyridine derivatives received considerable attention. Decarboxylative hydroxylation was an important degradation process in pyridine derivatives, and previously reported decarboxylative hydroxylations happened in the C3 of the pyridine ring. In this study, we cloned the gene cluster hpa, which is responsible for 5HPA degradation in Alcaligenes faecalis JQ135, thus identifying a novel monocomponent FAD-dependent monooxygenase HpaM. Unlike 3-decarboxylative monooxygenases, HpaM catalyzed decarboxylative hydroxylation in the C2 of the pyridine ring in 5-hydroxypicolinic acid. These findings deepen our understanding of the molecular mechanism of microbial degradation of pyridine derivatives. Furthermore, HpaM offers potential for applications to transform useful pyridine derivatives.

microbiology↗