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Microbes & Immunity

REVIEW ARTICLE
Staphylococcus aureus capsule: Production,

function, and regulation

Yifan Rao 1 , Zuwen Guo 2 , Huagang Peng 2 , Xiancai Rao * , and
2
Guixue Wang *
1,3
1 Key Laboratory of Biorheological and Technology of the Ministry of Education, State and Local Joint
Engineering Laboratory for Vascular Implants, Modern Life Science Experiment Teaching Center at
Bioengineering College of Chongqing University, Chongqing, China
2 Department of Microbiology, College of Basic Medical Sciences, Key Laboratory of Microbial
Engineering under the Educational Committee in Chongqing, Army Medical University (Third Military
Medical University), Chongqing, China
3 Jinfeng Laboratory, Chongqing, China

Abstract

Staphylococcus aureus is a major opportunistic pathogen that causes a wide
spectrum of human and animal diseases. Capsule is one of the key virulence factors of
S. aureus. Approximately 90% of S. aureus isolates produce capsular polysaccharides
(CPs) that envelop the entire bacterial cells. CPs can suppress the phagocytosis of
S. aureus by innate immune cells, promote intracellular survival, and reduce the
killing efficacy of antimicrobial agents. As a result, CPs are versatile candidates for
vaccine development. The synthesis of S. aureus CPs is controlled by the cap operon,
*Corresponding authors:
Xiancai Rao which contains 16 genes encoding functional enzymes involved in the biosynthesis
(xcrao@tmmu.edu.cn) and transport of CPs. During S. aureus growth, cap operon expression is strictly
Guixue Wang regulated. The control region of the cap operon is characterized by two promoters:
(wanggx@cqu.edu.cn)
a housekeeping sigma factor A (SigA)-dependent promoter and a stress-responsive
Citation: Rao Y, Guo Z, Peng H, sigma factor B-dependent promoter. Many transcription factors, including both
Rao X, Wang G. Staphylococcus
aureus capsule: Production, positive and negative regulatory molecules, are timely involved in the regulatory
function, and regulation. Microbes & network of S. aureus capsule synthesis. Moreover, environmental conditions such as
Immunity. 2025;2(4):1-16. medium composition and carbon dioxide levels further modulate CP production.
doi: 10.36922/mi.8392
In this review, the structure and function of S. aureus CPs are introduced, and the
Received: January 3, 2025 biosynthesis of S. aureus CPs is discussed. Moreover, the regulation of S. aureus CP
Revised: April 9, 2025 production is summarized, the factors affecting CP production are outlined, and the
preparation of S. aureus CPs is reviewed. The advanced information presented here
Accepted: April 15, 2025
may provide useful references for further research on the production and function of
Published online: May 2, 2025 S. aureus CPs.
Copyright: © 2025 Author(s).
This is an Open-Access article
distributed under the terms of the Keywords: Staphylococcus aureus; Capsular polysaccharides; Immune evasion; Cap
Creative Commons Attribution operon; Virulence factors; Capsule purification
License, permitting distribution,
and reproduction in any medium,
provided the original work is
properly cited.
1. Introduction
Publisher’s Note: AccScience
Publishing remains neutral with Staphylococcus aureus is a Gram-positive opportunistic pathogen that commonly
regard to jurisdictional claims in 1
published maps and institutional colonizes the skin, nasopharynx, and mucosal surfaces of healthy individuals. Under
affiliations. conditions of immune suppression or epithelial barrier disruption, S. aureus can

Volume 2 Issue 4 (2025) 1 doi: 10.36922/mi.8392