Proteomic identification of Acanthamoeba castellanii excretory-secretory proteins associated with Klebsiella pneumoniae capsule enlargement: a candidate role for C-type lysozyme.

Chun-Hsien Chen, Jian-Ming Huang, Wei-Chen Lin, Chih-Ming Tsai, Hsin-Yu Hsieh, Yu-Jen Wang

Abstract read

In one paragraph

Article in Parasite (Paris, France), 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

0numbers the graph read from it

0cells of the map it votes in

0citing papers in PubMed

–field-weighted citation impact

1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

0 citing papers in PubMed.

No citing paper in PubMed yet.

4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

6 authors.

Chun-Hsien ChenGraduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan - Department of Parasitology, College of Medicine, Chang Gung University, Taoyuan City, Guishan Dist., Taiwan.

Jian-Ming HuangSchool of Medicine, National Tsing Hua University, Hsinchu, Taiwan - Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu, Taiwan.

Wei-Chen LinDepartment of Parasitology, College of Medicine, National Cheng Kung University, Tainan, Taiwan - Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.

Chih-Ming TsaiDepartment of Parasitology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.

Hsin-Yu HsiehDepartment of Nursing, Feng Yuan Hospital, Ministry of Health and Welfare, Taichung, Taiwan.

Yu-Jen WangDepartment of Parasitology, School of Medicine, China Medical University, Taichung, Taiwan - Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan - Departments of Laboratory Medicine and Internal Medicine, China Medical University Hospital, Taichung, Taiwan.ORCID 0000-0002-2981-9429

Funding

China Medical University, Taiwan CMU114-S-34Ministry of Health and Welfare MOHW-YFH-11419National Science and Technology Council NSTC 115-2320-B-039-061-MY3

6 · The paper itself

Abstract

backgroundAcanthamoeba castellanii and Klebsiella pneumoniae are environmental commensals that co-exist in aquatic habitats. Our previous studies demonstrated that A. castellanii genotype T4 (AcT4) induces capsule enlargement and hypermucoviscosity in K. pneumoniae through small excretory-secretory proteins (ESPs; <10 kDa) that activate the Rcs two-component system, upregulating capsule biosynthesis genes independently of virulence plasmids. However, the molecular identity of these active ESPs remained undefined.

resultsTo identify candidate proteins, we performed label-free quantitative proteomics (LC-MS/MS) on conditioned medium from AcT4 co-cultured with K. pneumoniae (Ac/Kp) versus AcT4 alone (Ac only; n = 3 per group). A total of 391 A. castellanii proteins were identified; seven showed significantly increased extracellular abundance in Ac/Kp medium (log

conclusionsThis comparative secretome analysis provides the first proteomic catalogue of AcT4 extracellular proteins during co-culture with K. pneumoniae and identifies C-type lysozyme as a biologically plausible candidate mediating Rcs-dependent capsule induction. These findings lay the groundwork for future validation of AcT4-derived ESPs in protozoa-bacteria interactions and their potential role in the environmental emergence of hypervirulent K. pneumoniae.

Indexed as

Acanthamoeba castellaniiBacterial CapsulesKlebsiella pneumoniaeMuramidaseProtozoan ProteinsChromatography, LiquidCoculture TechniquesProteomicsTandem Mass SpectrometryMuramidaseProtozoan ProteinsAcanthamoeba castellaniiKlebsiella pneumoniaeLabel-free proteomicsLysozymeRcs two-component systemSecretome

Identifiers

PMID42825505

DOI10.1051/parasite/2026057

PMCPMC13632502

What OpenQuestion holds

Textmetadata

Read underepoch 390

Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.