gliding

Deep research

Generated by just research-trait; source: research/traits/morphology/gliding-deep-research-falcon.md

# Curation report: microbial gliding

## 1. Scope and recommended interpretation

**Target:** `METPO:1000706`  
**Category:** MORPHOLOGY; **term kind:** CLASS; **parent:** `METPO:1000702`; **mapping:** REVIEWED.

For TraitMech, gliding should denote **active, energy-dependent translocation of a microbial cell along a solid or semisolid interface without flagellar propulsion**. Canonical *Flavobacterium* gliding uses moving cell-surface adhesins, whereas *Myxococcus xanthus* adventurous/A-motility uses a trans-envelope Agl–Glt focal-adhesion system. These systems are mechanistically nonhomologous and should be represented as separate branches converging on `METPO:1000706`. *F. columnare* glides on fish tissue, glass, agar, and other surfaces and forms spreading colonies on agar, illustrating both the biological phenotype and common assays. (vincent2022dynamicprotondependentmotors pages 1-2, thunes2024glidingmotilityproteins pages 1-2, jolivet2023integrinlikeadhesincgld pages 1-3)

The supplied wording—“moves smoothly along solid surfaces without flagella or pili”—is appropriate for canonical *Flavobacterium* motility and *M. xanthus* A-motility. It should **not** be applied indiscriminately to every historical use of “gliding,” because some cyanobacterial literature uses that label for type-IV-pilus-related movement.

### Boundary cases

- **Exclude swimming:** movement through liquid driven by flagella or other swimming machinery.
- **Exclude twitching/social motility:** type IV pilus extension–retraction. In *M. xanthus*, S-motility is twitching, whereas A-motility is the gliding branch. (chen2022flagellarmotortransformed pages 1-2)
- **Exclude passive sliding:** colony expansion driven chiefly by growth, surfactants, or reduced friction without an active cell-autonomous motor.
- **Do not equate colony spreading with gliding automatically:** spreading can combine growth, environmental conditions, collective organization, and several adhesins. Agar and glucose strongly alter *F. johnsoniae* colony morphology, and glucose can permit SprB-independent spreading on soft agar. (sato2021colonyspreadingof pages 1-3)
- **Swarming is separate:** normally a coordinated, flagellum-dependent surface behavior.
- **Mycoplasma gliding:** a genuine but mechanistically distinct ATP-driven branch. Because adequate full-text evidence was not recovered here, its machinery should not be added to this graph from this report alone.

## 2. Current mechanistic understanding

### Bacteroidota/*Flavobacterium* branch

The best-supported causal chain is:

**transmembrane proton gradient → GldL/GldM motor → T9SS-dependent SprB export and surface motion → transient SprB–substratum adhesion → cell-body displacement → gliding.**

Vincent et al. directly showed that the pH-gradient component of proton motive force powers *F. johnsoniae* gliding. GldL and GldM form dynamic membrane channels; conserved glutamates in GldL TMH2 are required; and PMF-dissipating inhibitors prevent secretion and halt cell displacement. SprB follows a closed helical path, and its substrate binding converts relative adhesin motion into screw-like forward displacement. The paper was published **25 March 2022**. (vincent2022dynamicprotondependentmotors pages 1-2)

The apparatus is intertwined with the type IX secretion system (T9SS). GldK, GldL, GldM, and GldN are shared core components, while some factors are branch-specific. PorV can be required for secretion of many type-A CTD substrates without eliminating SprB-dependent movement, whereas SprB is principally a motility adhesin. Thus, “T9SS activity” and “gliding” should be separate nodes rather than treated as equivalent phenotypes. (thunes2024glidingmotilityproteins pages 2-5, thunes2024glidingmotilityproteins pages 1-2)

### *Myxococcus xanthus* A-motility branch

The approximately 20-component Agl–Glt apparatus spans the cell envelope. Its AglR/Q/S energy-harvesting unit is homologous to MotA/B-family flagellar stators and operates as a proton-channel motor. Motors move helically in an MreB-dependent manner and become stationary relative to the substratum at force-generating bacterial focal adhesions. MreB disruption abolishes helical motor motion and blocks gliding, although whether MreB is a direct track remains unresolved. Motor aggregation also increases on harder substrates, supporting a mechanosensing model. These conclusions were synthesized in a peer-reviewed perspective published **6 May 2022**. (chen2022flagellarmotortransformed pages 1-2)

A **19 October 2023 bioRxiv preprint** proposed that CglB engagement immobilizes the Agl–Glt complex at focal-adhesion sites, enabling force transmission. It further identified CglD as a calcium-dependent, integrin-like outer-membrane lipoprotein that anchors and stabilizes the Glt–CglB assembly. The work used traction-force, bead-force, TIRF microscopy, and biochemical methods, but its preprint status requires an uncertainty flag. (jolivet2023integrinlikeadhesincgld pages 1-3)

## 3. Candidate nodes

### Trait and processes

- gliding — `METPO:1000706`
- cell motility — `GO:0048870`
- surface-associated locomotion — label-only
- bacterial focal-adhesion assembly — label-only
- trans-envelope force transduction — label-only
- mechanosensing — label-only
- type IX secretion — label-only pending curator verification of an exact ontology term
- colony spreading — label-only; assay readout, not synonymous with gliding
- virulence in fish — label-only; downstream application phenotype

### Energy, chemicals, and experimental factors

- proton — `CHEBI:15378`
- transmembrane proton gradient / proton motive force — label-only
- calcium(2+) — `CHEBI:33070`
- glucose — `CHEBI:17234` should be curator-verified before use; retain label-only if not verified locally
- carbonyl cyanide *m*-chlorophenyl hydrazone (CCCP) — label-only pending identifier verification
- solid substratum, glass, agar, fish tissue — label-only or ENVO-grounded after exact-term verification

Showing the first 60 of 205 lines of findings; the linked file also carries the run's front matter and the prompt it was given — read the full report.