# Enzymatic Mechanism of Polysaccharide Length Control by GlfT2

> **NIH NIH F31** · MASSACHUSETTS INSTITUTE OF TECHNOLOGY · 2024 · $48,974

## Abstract

PROJECT SUMMARY/ABSTRACT
Extracellular polysaccharides play critical roles across all domains of life. Bacterial polysaccharides are a
diverse class of macromolecules with multiple biological functions, including mediating interactions with the
external environment and preserving cell wall integrity. Bacterial glycosyltransferases are responsible for
polysaccharide diversity through their differences in substrate specificity and linkage production.
Polysaccharide biosynthesis and elongation can occur by multiple mechanisms; the least understood is
processive polymerization. Processivity is elicited from an enzyme’s ability to retain the acceptor through
numerous elongation steps. This process reduces the production of short-length polysaccharides, which could
be harmful to bacterial fitness. Processivity may represent a common and critical mechanism for
polysaccharide biosynthesis and length control.
Production of the mycobacterial galactan by galactofuranosyltransferase 2 (GlfT2) was shown to proceed by a
processive mechanism. The galactan of Mycobacterium spp. is an essential structural glycan, functioning as a
component of the cell wall structure of human pathogens including Mycobacterium tuberculosis and
Mycobacterium leprae. Galactan truncation decreases cell fitness, promotes periplasm thinning, and increases
antibiotic susceptibility. Therefore, enzymatic processivity by GlfT2 likely ensures the galactan is of sufficient
length. The proposed studies seek to define the mechanism of GlfT2 processivity and the biophysical
parameters that dictate product length distributions. This project encompasses training in enzyme production
and characterization, enzyme kinetics assays, and enzyme structure determination. The Kiessling group,
leaders in chemical glycobiology, and the Department of Chemistry at MIT provide a rich environment to
acquire these research skills. The research environment also offers opportunities to engage in science
communication, literature analysis, and career development. The results from the investigations proposed are
expected to provide a framework for mechanistic analysis of processive glycosyltransferases found in other
bacteria and across the different domains of life. New insights into this under-characterized class of enzymes
will provide novel targets to combat the modern emergence of antibiotic-resistant bacteria.

## Key facts

- **NIH application ID:** 10909396
- **Project number:** 5F31GM148069-03
- **Recipient organization:** MASSACHUSETTS INSTITUTE OF TECHNOLOGY
- **Principal Investigator:** Alan Wylde Carter
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $48,974
- **Award type:** 5
- **Project period:** 2022-08-18 → 2025-08-17

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10909396

## Citation

> US National Institutes of Health, RePORTER application 10909396, Enzymatic Mechanism of Polysaccharide Length Control by GlfT2 (5F31GM148069-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10909396. Licensed CC0.

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